Chapter 2 Outline–Genes, Environment, and Development PDF

Chapter 2 Outline–Genes, Environment, and Development 2.1 Evolution and Human Development 1. Focus of Heredity Descriptions a. Role in creating differences among individuals i. Genetic variations (e.g., eye color, blood type) ii. Inheritance of...

Chapter 2 Outline–Genes, Environment, and Development 2.1 Evolution and Human Development 1. Focus of Heredity Descriptions a. Role in creating differences among individuals i. Genetic variations (e.g., eye color, blood type) ii. Inheritance of specific traits 2. Commonalities Among Humans a. Universal physical characteristics i. Two eyes and blood circulation b. Similar developmental milestones i. Walking and talking around age 1 ii. Sexual maturation between ages 10-14 iii. Aging processes (e.g., skiing wrinkling in 40s and 50s) 3. Definition: Species Heredity a. Definition and significance i. Genetic endowment common to a species ii. Influence on developmental and aging processes b. Comparison to other species i. Unique capacities (e.g., language, empathy) ii. Distinctions between species (e.g., humans vs. birds) 4. Genetic similarities a. Universality of certain patterns b. Conclusion on genetic commonality among humans Darwin’s Evolutionary Theory 1. Introduction to Evolutionary Theory a. Importance of Charles Darwin’s work i. Lifetime: 1809-1882 ii. Overview of Darwin’s theory of evolution (Darwin, 1859) b. Controversial nature of the theory c. Influence on the study of human development 2. Main Arguments of Darwin’s Theory a. Genetic variation in a species i. Presence of different genes among species members ii. Impact on species adaptation over time b. Differential adaptation of genes i. Some genes aid adaptation (e.g., strength, intelligence) ii. Benefits for survival and resource acquisition 3. Key Term: Natural Selection a. Definition and key principles i. Survival and reproduction based on advantageous genes b. Frequency of advantageous genes in future generations i. Increasing commonality of genes that enhance survival ii. Role of reproduction in genetic transmission 4. Long-Term Changes in Species a. Gradual changes in genetic makeup over time b. Potential for new species to emerge  c. Darwin observations on the Galapagos Islands i. Resulting diversity of species well adapted to their environments 5. Introduction to the Study of Moths a. Research by HBD Kettlewell (1959) b. Focus on genetic variations among moths i. Dark and light colored variations 6. Environmental Impact on Survival a. Rural areas i. Survival of light-colored moths ii. Camouflage against light-colored trees iii. Advantage from natural selection b. Industrial areas i. Survival of dark moths ii. Camouflage against darkened trees iii. Increased vulnerability of light moths 7. Changes in Moth Populations a. Impact of industrialization on moth colorization i. Increase in dark moth population b. Effects of population control i. Resurgence of light-colored moths in cleaner areas 8. Conclusion a. Illustration of natural selection in action b. Adaptive changes in response to environmental conditions  9. Evolution Beyond Genetics a. Interaction between genes and environment b. Contextual nature of genetic advantages 10. Environmental Influences on Genetic Advantage a. Variation in survival based on environmental conditions i. Adaptive traits in specific environments ii. Maladaptive traits in contrasting environments 11. Changing Demands of Modern Environments a. Historical vs. contemporary advantages i. Genes for hunting prey vs. modern skills b. Importance of traits relevant to today’s society i. Mastery of technology (e.g., iPhone apps, Excel spreadsheets) 12. Evolutionary Theory and Human Development a. Role of shared species heredity i. Evolution through natural selection ii. Impact of ancestral environments 13. Moving beyond “Nature vs. Nurture” a. Intertwining of genetic and environmental factors b. Modern understanding in evolutionary theory i. Importance of both forces in development Modern Evolutionary Perspectives 1. Influence of Evolutionary Theory on Human Development a. Historical significance in the field  b. Contemporary appreciation 2. Development of Ethology a. Definition and purpose i. Understanding evolved behavior in natural environments b. Key figures in ethology i. Konrad Lorenz ii. Niko Tinbergen 3. Key Questions in Ethology a. Innate behaviors and their adaptive value i. Examples from animal behavior studies b. Case study: birds and their songs i. Recording and analysis of birdsongs ii. Learning songs and their role in reproduction and survival 4. Human Behaviors and Evolution a. Species-specific behaviors in humans b. Attachment theory i. Development by John Bowlby ii. Influence of ethology on attachment theory iii. Evolutionary basis for attachment between infants and caregivers 5. Definition of Modern Evolutionary Psychology a. Application of evolutionary perspective b. Understanding human development, thought, and behavior 6. Fundamental Questions in Evolutionary Psychology  a. Characteristics and behaviors of humans i. Adaptations to environments ii. Genetic endowment of the species b. Nature of human behavior i. Cooperative vs. selfish tendencies ii. Moral vs. aggressive behaviors 7. Evolutionary Origins of Human Traits a. Evolution of brain functions i. Recognizing faces ii. Understanding thoughts and feelings b. Gender differences and their evolutionary origins c. Human mating and parenting strategies i. Choices in sexual partners ii. Parenting behaviors 8. Evolutionary Developmental Theorists a. Michael Tomasello’s contributions i. Unique human abilities to collaborate and cooperate ii. Early-developing tendencies in children 1. Helping and sharing 2. Conforming to group norms b. Adaptive significance of these theories Life History Strategies 1. Mating Strategies  a. Characteristics of a mating strategy i. Seeking multiple partners ii. Focus on maximizing reproductive opportunities b. Ecological and social factors influencing mating strategies 2. Parental Investment Strategy a. Characteristics of parental investment strategy i. Settling on a mate ii. Investing in a smaller number of offspring b. Biological factors influencing parental investment i. Maternal investment (gestation and lactation) ii. Parental roles and involvement 3. Differences in Investment Between Mothers and Fathers a. Statistical overview of parental investment in mammals b. Reasons for greater maternal investment c. Factors influencing paternal involvement i. Certainty of paternity ii. Availability of mating opportunities 4. Interplay of Strategies a. Variability among individuals and species b. Influence of cultural and environmental factors c. Implications for understanding human behavior and family dynamics 5. Variation in Reproductive Strategies  a. Some cultures/subcultures rely on parental investment (focused on long-term care of fewer offspring) b. Others focus on the mating strategy (emphasizing reproduction with multiple partners and less long-terms investment) 6. Evolutionary Psychologists’ Hypothesis a. Early experiences help individuals learn which reproductive strategy is most adaptive in their environment b. This shapes their future reproductive behavior 7. Life History Strategies a. Humans adopt one of two strategies based on their environment: i. Slow-track strategy: prioritizes long-term care, fewer offspring, and greater parental investment ii. Fast-track strategy: Emphasizes early reproduction, more offspring, and less parental investment 8. Adoption of Slow-Life History Strategy a. More likely in secure and predictable environments b. Characteristics of the slow-life history strategy: i. Parents are supportive of children ii. Sex and childbearing are postponed during adolescence until resources are available iii. New couples form long-term relationships iv. Parents invest significant energy in raising a small family v. Children have a higher chance of survival 9. Adoption of Fast-Life History Strategy a. More likely in stressful environments, characterized by: i. High crime, poverty, and death rates ii. Unstable families and limited work opportunities b. Characteristics of the fast-life history strategy i. Parenting tends to be less supportive compared to safe environments ii. Children learn to live in the present and may prioritize immediate gratification iii. Early and multiple sexual involvements are common iv. Unstable romantic relationships are prevalent v. Limited investment in raising children may occur c. Mating strategy over parental investment strategy for survival and gene passing 10. Findings From the Longitudinal Study by Lei Chang et al. (2019) a. Study involved parents and adolescence in nine countries b. Support for evolutionary life history theory: i. Harsh and unpredictable environments linked to fast-life history strategy adoption ii. Characteristics of the fast track: 1. Focus on the present and self-interest 2. Associated with aggressive behavior (aimed at obtaining resources and status) 3. Linked to poor academic performance (reflecting less long-term planning)  c. Children in safer, more predictable environments often adopted a slow-life history strategy: i. Demonstrated more positive social behavior ii. Performed better in school d. This relationship was evident across all nine countries studied 11. Modern Evolutionary Psychology Perspectives a. Research on fast versus slow-life history strategies provides insight into human development and behaviors b. Key points: i. Humans are not simply robots who act on instinctive behaviors directed by genes ii. Humans have evolved to learn which behaviors are adaptive in their specific cultures and communities Cultural Evolution 1. Changes in Human Environments a. Genetic makeup of the human species evolves slowly through biological evolution b. Parallel process: cultural evolution i. Definition: the process of inheriting characteristically human environments and adapting to them ii. Involves inventing better ways to adjust to changing conditions and passing on knowledge to future generations 2. Example of Cultural Evolution:  a. Adaptations do not require waiting for generations, such as: i. Inventing lighter fabrics and better air conditioners for warming climates ii. Teaching children methods of: 1. Building huts or condos 2. Cooking over fires or using microwaves 3. Sending smoke signals or text messages 3. Speed of Cultural Evolution a. Cultural evolution through learning and socialization occurs more quickly than biological evolution b. Accelerated by instant communication in modern society 4. Significance of Biological Evolution a. The legacy includes a large, powerful, and flexible brain i. Allows humans to: 1. Learn from experiences 2. Devise better ways to adapt to environments 3. Communicate learned knowledge to others 5. Impact on Childhood and Adolescence a. Evolution has resulted in an unusually long childhood and adolescence i. Provides time for brain development ii. Allows ample opportunity to learn essential cultural knowledge for contributing to society 2.2 Individual Heredity 1. Understanding How Genes Contribute to Human Differences  a. Begins at conception: i. The moment when an egg is fertilized by a sperm b. Examination of the working genes c. Consideration of mechanism through which genes influence traits The Genetic Code 1. Contribution of Sperm and Ovum to the Zygote a. Each contributes 23 chromosomes b. Total of 46 chromosomes in the zygote, organized into 23 pairs 2. Chromosomes and Genes a. Chromosomes: threadlike bodies in the nucleus of each cell b. Genes: i. Basic units of heredity ii. Located in stretches on chromosomes 3. Inheritance of Chromosome Pairs a. One member of each chromosome pair will come from the father b. One member of each chromosome pair will come from the mother Meiosis and Mitosis 1. Chromosome Count in Sperm and Ova a. Sperm and ova have 23 chromosomes, unlike other cells b. Produced through the process of cell division called meiosis 2. Meiosis Process: a. Begins with a reproductive cell in the ovum (female) or testes (male) containing 46 chromosomes  b. First division: cell splits into two 46 chromosome cells c. Second division: i. Each of the two cells splits again, forming four cells ii. Each resulting cell only has 23 chromosomes 3. End products of meiosis a. Female: i. One egg ii. Three nonfunctional cells that play no role in reproduction b. Male: i. Four sperm cells 4. Chromosome Distribution a. Each sperm of egg has only one member from each of the parent’s chromosome pairs 5. Timing of Gamete Formation: a. Ova: formed prenatally, ripen one by one during menstrual cycles b. Sperm: production begins at puberty and continues throughout adulthood 6. Sperm Cell Penetration of the Ovum a. Occurs a few hours after fertilization b. Sperm cells begins to disintegrate, releasing its genetic material 7. Release of Ovum’s Genetic Material a. The nucleus of the ovum releases its own genetic material b. A new cell nucleus is formed from the genetic information from both the mother and the father 8. Formation of the Zygote a. The new cell is called a zygote b. The zygote is the size of a pinhead c. This marks the occurrence of conception 9. Formation of a Multiple Celled Organism a. The single-celled zygote becomes a multiple-celled organism through mitosis 10. Process of Mitosis a. A cell and its 46 chromosomes divide to produce two identical cells, each containing 46 chromosomes b. The zygote moves through the fallopian tube to the uterus c. Cell division progression: i. Zygote divides into two cells ii. Two cells divide into four iii. Four becomes eight, and so one, all through mitosis 11. Role of Mitosis Through Growth and Repair a. All normal human cells, expect sperm and ova, contain 46 chromosomes b. Mitosis continues throughout life, creating new cells for growth and replacing damaged cells 12. Comparison of Mitosis and Meiosis a. Mitosis i. Begins at conception ii. Continues throughout the lifespan  iii. Produce two identical daughter cells, each with 46 chromosomes like its parent iv. Accomplishes growth of the human from a fertilized egg and renewal of the body’s cells b. Meiosis in males i. Begins in puberty ii. Continues throughout adolescence and adulthood iii. Produces four sperm, each with 23 chromosomes iv. Accomplishes the formation of male reproductive cells c. Meiosis in Females i. Occurs early in the prenatal period when unripened ova form ii. Continues throughout reproductive years, with one ovum ripening each month of the reproduction cycle iii. Produces one ovum and three nonfunctional polar bodies, each with 23 chromosomes iv. Accomplishes the formation of female reproductive cells Decoding the Genome 1. Role of Chromosomes in Human Development a. Each chromosome pair, one from the father and one from the mother, influences the same characteristics b. Chromosomes are made up of strands of deoxyribonucleic acid (DNA) c. DNA is the double helix molecule that contains genetic information 2. DNA Composition  a. DNA consists of four chemicals: i. Adenine (A) ii. Cytosine (C) iii. Guanine (G) iv. Thymine (T) b. Some DNA sequences are genes, the basic units of heredity 3. The Human Genome Project a. Completed in 2003 b. Mapped chemical units of DNA c. Revealed humans have around 20,000 gene pairs, less than previously estimated 4. Function of Genes a. Genes provide instruction of the production of proteins b. Proteins are essential for bodily tissues, hormones, neurotransmitters, and enzymes c. Genes can have different versions or variants 5. Non-Coding DNA a. About 2% of the human genome consists of genes traditionally defined as protein-coding b. The remaining 98% was one considered “junk” DNA c. These DNA segments regulate gene activity, turning genes on and off based on environmental influences Genetic Uniqueness and Relatedness 1. Genetic Differences Between Relatives  a. Chromosome separation during meiosis is random b. Each chromosome pair separates independently 2. Genetic Diversity in Sperm and Ova a. Each sperm or ovum contains 23 pairs of chromosomes b. A single parent can produce 8 million genetically different sperm or ova 3. Genetic Combinations in Offspring a. Any couple can produce 64 trillion genetically unique children b. Two two would have the same genome unless identical twins 4. Genetic Uniqueness of Children of the Same Parents a. Greater genetic diversity due to crossing over in meiosis b. Mechanism of crossing over i. Chromosome pairs exchange parts before separating ii. Comparison to exchanging fingers in a handshake c. Unlikelihood of identical genetic replication d. Exception: identical twins i. Definition of identical (monozygotic twins) ii. Result from one fertilized ovum dividing iii. Occurence in about 1 in every 250 births 5. Genetic Similarity Between Parent, Child, and Siblings a. Genetic contribution from parents i. 50% of genes from mother ii. 50% of genes from father b. Genetic resemblance among siblings  i. Average genetic resemblance of 50% ii. Variation in shared genes due to meiosis c. Differences in sibling similarities i. Some siblings are very similar, others are different 6. Dizygotic twins (fraternal twins) a. Definition and formation i. Result from two fertilized eggs ii. Each ovum is fertilized by a different sperm b. Prevalence i. Occurs in about 1 in every 125 births c. Genetic similarity i. No more alike genetically than siblings ii. Can be of different sexes d. Factors influencing occurrence i. Tendency to run in families ii. Increased prevalence due to fertility drugs and in vitro fertilization 7. Genetic resemblance among extended family a. Relationships and genetic sharing i. Grandparent and grandchild 1. Share 25% of genes on average ii. Aunt or uncle and niece or nephew 1. Also share 25% of genes on average iii. Half-brothers and half-sisters  1. Share 25% of genes on average b. Genetic uniqueness i. Every individual, besides, identical twins, is genetically unique c. Contribution to family resemblances i. Shared genes contribute to familial traits Determination of Sex 1. Chromosomes in Individuals a. Each individual inherits 23 pairs of chromosomes b. 22 pairs are similar in males and females 2. Sex chromosomes a. The 23rd pair consists of sex chromosomes b. Male children have one X chromosome and one Y chromosome c. Female children have two X chromosomes 3. Determining Gender a. A mother’s egg can only have an X chromosome b. A father’s sperm can either have an X or a Y chromosome 4. Genetic Male Development a. If an ovum with an X chromosome is fertilized by a sperm with a Y chromosome, the result is an XY zygote (a genetic male) b. A gene on the Y chromosome initiates male sexual development 5. Genetic Female Development a. If a sperm carrying an X chromosome fertilizes the ovum, the result is an XX zygote (a genetic female)  6. Historical Context a. Understanding of these genetic facts may have altered societal views regarding the birth of male heirs 7. Genetic Makeup of a Child a. A child has a genome with approximately 20,000 pairs of protein-coding genes b. The genome includes significant amounts of regulatory DNA c. Genes are arranged in 46 chromosomes in 23 pairs 8. Influence of Genes and Environment a. The relationship between genes and environmental factors affects individual characteristics and development b. Understanding of this relationship is evolving rapidly From Genotype of Phenotype 1. Environmental Influence on Genetic Expression a. Environmental factors help determine the translation of genetic codes into physical and psychological traits 2. Genotype vs. Phenotype a. Genotype refers to the genetic makeup a person inherits b. Phenotype refers to the characteristic or trait the person eventually has (e.g., height of 5 feet 8 inches) 3. Interaction of Genes and Environment a. An individual may have a genotype for exceptional height but may not be tell due to environmental factors  b. Severe malnutrition from the prenatal period onward can affect growth, regardless of genetic potential c. The combination of genes and environment determines how genotype translates into phenotype 4. Genes and Environmental Influence a. Genes guide the production of specific proteins b. Genes influence traits like eye color through melanin production c. Genetically coded proteins assist forming neurons and their connections, affecting intelligence and personality d. Genes are influenced by the biochemical environment surrounding them 5. Cell Differentiation a. During embryonic development, environmental factors determine cell specialization b. All cells share the same genes, but differences arise from which genes are expressed or activated 6. Gene Expression a. Activation of specific genes in particular cells at particular times influence phenotype b. Only “turned on” genes are influential 7. Influences on Gene Expression a. Genetic influences include the action of regulatory DNA b. Environmental influences include diet, stress, drugs, toxins, and early parenting 8. Research Excitement  a. Increased interest on how environmental factors can alter gene expression b. Epigenetic effects involve chemical coding that activate or deactivate genes c. The epigenome changes throughout development and registers environmental influences 9. Understanding Development a. Ongoing research reveals biochemical processes that transform a fertilized egg into a human b. Genes do not dictate or determine development 10. Interaction Between Genes and Environment a. Genetic influences cannot be separated from environmental influences b. Genes and environment co-act to influence gene expression c. Development is influenced throughout the lifespan Mechanisms of Inheritance 1. Basic Mechanisms of Inheritance a. Definition of Inheritance b. Overview of how parent’s genes influence children’s genotypes and phenotypes c. Three main mechanisms of inheritance: i. Single gene-pair inheritance ii. Sex-linked inheritance iii. Polygenic (or multiple-gene) inheritance Single Gene-Pair Inheritance 1. Single Gene-Pair Inheritance a. Influences thousands of human characteristics  b. Involves one gene from each parent 2. Gregor Mendel’s Contribution a. A 19th century monk recognized as the father of genetics b. Conducted cross-breeding of pea-plants and observed outcomes 3. Example of Mendelian Inheritance a. Approximately three-fourths of individuals can curl their tongues b. One-fourth cannot curl their tongues c. A dominant gene is associated with tongue curling d. A recessive gene is associated with the absence of the tongue-curling ability 4. Tongue Curling Genetics a. Inheritance of tongue-curling gene b. Gene labels i. U: tongue-curl gene (dominant) ii. -: no-cirl gene (recessive) c. Phenotype expression i. Possession of one U gene leads to tongue-curling d. Parental genotypes and offspring outcomes i. Reference to figure 2.2 for probabilities ii. Nine cells representing possible gene combinations iii. Explanation of gene contribution from both parents during conception 5. Genotype Combinations and Tongue Curling Probability a. Father with genotype UU (tongue curler) and mother with genotype - - (non-tongue curler)  i. Children inherit U- genotype (dominant tongue-curling gene and recessive no-curl gene) ii. 100% chance of having a tongue-curling child b. Genotype and phenotype relationship i. UU and U- both result in the tongue-curling phenotype c. Possibility of non-tongue curling children i. Both parents with U- genotype can have a non-tongue curling child genotype - -) ii. 25% chance for a non-tongue-curling child if recessive genes unite iii. Random outcomes, similar to card possibilities could result in all or no non-tongue-curling children iv. Non-tongue-curling parents (- - genotype) will only have non-tongue-curling children 6. Examples of Dominant and Recessive Traits a. Traits influenced by dominant and recessive genes i. Dominant traits: 1. Brown eyes 2. Dark hair 3. Nonred hair 4. Curly hair 5. Normal vision 6. Broad lips 7. Double-Jointedness  8. Pigmented skin 9. Type A or B blood ii. Recessive traits: 1. Hazel-green, hazel, or blue eyes 2. Blonde hair 3. Red hair 4. Straight hair 5. Nearsightedness 6. Farsightedness 7. Thin lips 8. Normal joints 9. Albinism 10. Type O blood b. Special inheritance patterns i. Incomplete dominance: blending of traits, such as light brown skin from dark-skinned and light-skinned parents ii. Codominance: both genes fully expressed, such as AB blood type Sex-Linked Inheritance 1. Sex-Linked Inheritance a. Definition of sex-linked inheritance i. Characteristics influenced by genes on sex chromosomes ii. Mostly X-linked genes, fewer associated with the smaller Y chromosomes 2. Red-Green Color Blindness  a. Prevalence in males compared to females b. Cause of red-green color blindness i. Recessive gene located on X chromosomes ii. Y chromosome is shorter and contains fewer genes c. Inheritance patterns i. Boys inherit X chromosome from mother ii. No dominant gene on Y chromosome to counteract recessive gene d. Girls and red-green colorblindness i. Typically inherit a normal color-vision gene on the other X chromosome ii. Need to inherit two recessive genes to be color blind. 3. Hemophilia a. Definition and affects i. Blood clotting deficiency b. Prevalence among males compared to females i. Associated with recessive gene on X chromosomes Polygenic Inheritance 1. Polygenic Inheritance a. Contrat with single-gene influence i. Traits influenced by multiple pairs of genes ii. Interaction with environmental factors 2. Examples of Polygenic Traits a. Height b. Weight  c. Intelligence d. Personality e. Susceptibility to cancer and depression 3. Polygenic Traits and Variation a. Degrees of traits based on inherited gene combinations i. High-IQ genes vs. low-IQ genes ii. Most people inherit a mix of genes, leading to average traits 4. Normal Distribution of Traits a. Bell-shaped curve i. Majority near the average ii. Few people at the extremes b. Applies to intelligence and most measurable traits 5. Complexity of Gene Influence a. Uncertainty about the number of gene pairs involved i. Many genes with small effects b. Role of environmental influences in trait development Mutations and Copy Number Variations 1. Mechanisms of genetic influences on traits a. Single gene-pair inheritance b. Sex-linked inheritance c. Polygenic inheritance 2. Mutations a. Definition: Changes in the structure or arrangement of a gene  b. Nature of mutations i. Can be harmful or beneficial ii. Impacts depends on the environment c. Example: Hemophilia introduced by Queen Victoria’s descendents i. Caused by either sex-linked inheritance or spontaneous mutation d. Causes of mutations i. Increased by environmental hazards (e.g., radiation, toxic waste) ii. Mostly spontaneous errors during cell division iii. Fathers contribute more mutations than mothers iv. Risk of mutations increases with paternal age 3. Copy Number Variations (CNVs) a. Definition: deletion or duplication of a whole segment b. Comparison with mutations i. CNVs are more extensive than single-gene mutations ii. CNVs can affect multiple genes c. CNV effects i. Can result in having one or several copies of a gene d. Causes of CNVs i. Can be spontaneous or inherited 4. Impact of CNVs on Polygenic Disorders a. Disorders associated with CNVs i. Autism ii. Schizophrenia  iii. Bipolar disorder iv. ADHD v. Alzheimer’s disease b. CNVs are now prenatally tested for Chromosome Abnormalities 1. Chromosome Abnormalities and Human Development a. Definition of chromosome abnormalities i. Involved receiving too many or too few chromosomes ii. Abnormal chromosomes at conception b. Causes of chromosome abnormalities i. Errors during meiosis ii. Production of ovum or sperm with abnormal chromosome numbers c. Impact on pregnancy i. Most zygotes with abnormal chromosome numbers are spontaneously aborted ii. Main cause of pregnancy loss 2. Down Syndrome (Trisomy 21) a. Definition and characteristics i. Associated with three copies of the 21st chromosome ii. Distinctive features: eyelid folds, short limbs, thick tongues b. Intellectual functioning i. Varies widely among individuals ii. Most have some degree of intellectual disability (IQ below 70)  c. Developmental impact i. Slower pace of learning compare to peers ii. Benefits from early stimulation programs, special education, and vocational training 3. Life-Expectancy and Health in Individuals with Down Syndrome a. Challenges in less-developed regions i. Higher infant mortality rates due to heart defects b. Outcomes in developed countries i. Many individuals live into middle age and beyond ii. Signs of premature aging, including early Alzheimer’s disease 4. Incidence of Down Syndrome a. Prevalence in the United States i. Approximately 12 birth per 10,000 5. Determinants of Having a Child With Down Syndrome a. Role of chance i. Errors in meiosis can occur in any parent b. Impact of parental age i. Increased risk with maternal age, especially after 35 ii. Influence of paternal age 6. Risk Comparison by Age a. Couples over 40 i. About six times the risk of having a child with Down Syndrome compared to under 35 7. Chromosome Abnormalities and Meiosis Errors a. Overview of sex chromosome abnormalities i. Result from receiving too many or too few sex chromosomes ii. Attributed to mainly errors in meiosis iii. Increased likelihood with older parents and environmental hazards 8. Turner Syndrome a. Definition and prevalence i. Affects females with a single X chromosome (XO) ii. Occurs in about 1 in every 2,000-3,000 births b. Characteristics i. Typically small and underdeveloped ii. Preference for traditionally feminine activities iii. Lower-than-average spatial and mathematical abilities 9. Klinefelter Syndrome a. Definition and prevalence i. Affects males with one or more extra X chromosomes (XXY) ii. Occurs in about 1 in every 500-1,000 births b. Characteristics i. Tend to have long limbs, big ears, and long faces ii. May show feminine characteristics at puberty (e.g., enlarged breasts) iii. Most have normal IQs, may may experience language learning disabilities 10. XYY Syndrome a. Definition and prevalence  i. Affects makes with an extra Y chromosome (XYY) ii. Occurs in about 1 in 1,000 births b. Characteristics i. Tend to be tall and strong ii. Often experience learning disabilities c. Common misconceptions i. Belief linking XYY syndrome to aggression and criminal behavior is not well supported Genetic Diseases and Their Diagnosis 1. Impacts of Genetic Disorders on Human Development a. Types of genetic disorders i. Single gene or pair of genes ii. Polygenic disorders iii. Mutations and copy number variations iv. Chromosome abnormalities b. Rarity and Profound Effects on Development i. Reference sources for further information 2. Advancement in Genetic Counseling a. Increased information about genetic disorders b. Methods for DNA collection and analysis i. Cheek swabs ii. Small blood samples c. Role of genetic counselors in interpreting results  3. Case studies in Genetic Disorders a. Sickle-cell disease b. Huntington’s disease c. Phenylketonuria Sickle-Cell Disease 1. Overview of Sickle-Cell Disease a. Definition and characteristics i. Blood disease affecting red blood cells ii. Sickle shape leads to entanglement and reduced oxygen distribution iii. Results in breathing problems and pain 2. Genetic origins and evolution a. Mutation and natural selection i. Mutation likely provided protection against malaria ii. Increased prevalence in Africa, Central America, and other tropical regions iii. Common among African Americans 3. Impact on Life Expectancy a. Historical context i. Average life expectancy was around 14 years ii. Common causes of early death: blood clots, strokes, heart failure, kidney failure b. Improvements in treatment i. Advances have increased average life expectancy to around 50 years  ii. Ongoing challenges for adults with the condition 4. Management of Sickle Cell Disease a. Coping with pain episodes i. Frequent blood transfusions ii. Use of pain medication 5. Genetic Makeup of Sickle-Cell Disease Carriers a. Prevalence among African Americans i. Approximately 9% have the genotype Ss b. Explanation of genotype i. Dominant gene (S) for round blood cells ii. Recessive gene (s) for sickle-shaped blood cells c. Implications of being a carrier i. Carriers do not have the disease ii. Potential to transmit the gene to offspring iii. Chance of having a child with sickle-cell disease if both parents are carriers 6. Risk of Sickle-Cell Disease in Offspring a. Genetic probability from two carriers (Ss x Ss) i. 25% chance of having a child with sickle-cell disease (ss) ii. 50% chance of having a child who is a carrier 7. Screening and Early Intervention a. Newborn screening practices in the United States i. Use of blood test to screen for sickle-cell disease  b. Treatment options for infected children i. Blood transfusions ii. Antibiotics to prevent infections iii. Hydroxyurea to prevent sickling of blood cells c. Benefits of early interventions i. Optimization of intellectual development 8. Future Directions in Treatment a. Experiments in gene editing i. Potential to insert genes generating round blood cells b. Screening challenges in less-developed regions i. Areas with high rates of sickle-cells disease in Sub-Saharan Africa and Central India ii. Lack of newborn screening programs 9. Association with Other Genetic Disorders a. Context of sickle-cell disease among other disorders linked to single pair of recessive genes Huntington’s Disease 1. Overview of Huntington’s Disease a. Definition i. A genetic disorder associated with a single dominant gene b. Age of onset i. Typically strikes in middle age 2. Impact on Health  a. Distribution of gene expression in the nervous systems b. Symptoms i. Motor problems ii. Personality changes iii. Dementia or loss of cognitive abilities 3. Inheritance Patterns a. Chance of inheritance i. Child Of a parent with the Huntington’s gene has a 50% chance of having the phenotype 4. Genetic Testing and Personal Choices a. Availability of genetic testing for Huntington’s disease b. Decision to undergo testing i. Some relative prefer uncertainty over knowing they will develop the disease ii. Psychological implications of knowing one’s genetic status Phenylketonuria 1. Overview of Phenylketonuria a. Definition i. Metabolic disorder caused by a single pair of recessive genes b. Consequences i. Results in brain damage and intellectual disability 2. Prevalence and Inheritance a. Carrier rate  i. About 1 in 50 people in the United States are carriers for the PKU gene b. Chance of having an infected child i. Two carriers have a 25% chance of having a child with PKU 3. Pathophysiology a. Lack of critical enzyme i. Needed to metabolize phenylalanine b. Effects of accumulation i. Converted to harmful acid that attacks the nervous system ii. Causes intellectual disability and hyperactivity 4. Screening and Management a. Newborn screening i. Routine blood test for PKU b. Dietary intervention i. Special diet low in phenylalanine ii. Importance of maintaining the diet to prevent deterioration of intellectual functioning 5. Long-Term Effects a. Adult health risks i. High levels of phenylalanine linked to inattention, hyperactivity, and anxiety 6. Comparison with Other Genetic Disorders a. Illustration of genetic diseases and disorders associated with a single gene or gene pair  b. Summary of conditions discussed Prenatal Diagnosis 1. Prenatal Diagnosis Procedures a. Purpose i. Detect abnormalities in prospective parents b. Techniques i. Ultrasound ii. Amniocentesis iii. Chorionic villus sampling (CVS) iv. Maternal blood sampling for fetal DNA v. Preimplantation genetic diagnosis 2. Prenatal Detection for Abnormalities a. Overview i. Importance for pregnant women, especially over 35 b. Techniques comparison i. How much can be learned ii. Pros and cons of each technique 3. Ultrasound a. Description i. Use of sound waves to create a visual image of the fetus b. Benefits i. Indicates number of fetuses, the sex, and viability ii. Detects visible physical abnormalities  iii. Considered very safe 4. Amniocentesis a. Procedure i. Needle inserted to withdraw amniotic fluid b. Detection capabilities i. Chromosome abnormalities ii. DNA analysis for single gene-pair disorders c. Risks i. Low risk of miscarriage ii. Safe after 15 weeks of pregnancy 5. Chorionic Villus Sampling a. Procedure i. Catheter inserted to extract chorion hair cells b. Detection capabilities i. Same as amniocentesis c. Advantages i. Performed as early as the 10th week of pregnancy 6. Maternal Blood Sampling for Fetal DNA a. Description i. Tests mother’s blood for chemicals and fetal DNA b. Benefits i. Can detect Down Syndrome with near 100% accuracy at 9-10 weeks ii. Poses no risk to the fetus  c. Follow-up i. Usually advised if an abnormality is detected 7. Preimplantation Genetic Diagnosis a. Description i. Involves in vitro fertilization and DNA analysis b. Benefits i. Implantation of only healthy embryos c. Target audience i. Couple at high risk for serious genetic conditions 8. Overall Benefits of Prenatal Diagnostic Techniques a. Prevention of serious disorders b. Opportunities for early interventions c. Example of neonatal DNA sequencing for newborns in intensive care 9. Ethical Considerations a. Concerns regarding increased abortion rates b. Possibility of “designer” babies c. Societal implications for prospective parents 10. Parental Reactions to Genetic Testing Results a. Relief for parents of typically developing embryos or fetuses b. Agonizing choices for parents of fetuses with serious defects c. Lack of definitive tests for polygenic conditions 11. Role of Genetic Counselors a. Education provided by genetic counselors  b. Correcting misunderstandings about genetic conditions 12. Importance of Genetic Education a. Encouragement to learn about genetic conditions in family history b. Value of seeking counseling when appropriate 2.3 Studying Genetic and Environmental Influences 1. Behavioral Genetics and Study of Trait Variation a. Behavioral genetics focuses on the contribution of genetic and environmental differences to variations in physical and psychological traits b. It is impossible to isolate the exact percentage of heredity vs. environment in determining a trait for an individual c. Heritability is used to estimate the proportion of trait variability attributed to genetic differences in a population 2. Role of Genetic and Environmental Factors a. Behavioral geneticists study both genetic and environmental contributions to developmental differences b. Non-genetic trait variability is linked to environmental differences 3. Animal Studies in Behavioral Genetics a. Experimental breeding studies are used to show genetic influences on traits like learning ability, activity level, and emotionality in animals b. Selective breeding of animals with certain traits demonstrates the heritability of those traits over generations 4. Human Studies in Behavioral Genetics  a. Humans cannot be selectively bred, so researcher rely on family, twins, and adoption studies to assess the relationship between genetic similarity and trait similarity b. Molecular genetics techniques are increasingly used to study the effects of specific genes on traits Twin, Adoption, and Family Studies 1. Twins as Sources of Evidence for Heredity Effects a. Twin studies compare identical twins reared together with fraternal twins to untangle genetic and environmental differences b. Identical twins share 100% of their genes, while fraternal twins share 50% on average c. More complex twin studies examine identical and fraternal twins reared apart and together to differentiate between genetic and environmental differences 2. Limitations of the Twin Method a. Identical twins may share a more similar prenatal environment than fraternal twins, leading to increased psychological similarity b. Identical twins are often treated more similar than fraternal twins, which may account for some of their psychological similarity c. Psychological similarity is more likely to be genetically based rather than a result of treatment 3. Adoption Studies in Behavioral Genetic s a. Adoption studies examine whether children resemble their biological parents (genetic influence) or their adoptive parents (environmental influence)  b. Children’s psychological similarity to biological parents supports genetic influence, while similarity to adoptive parents supports environmental influence 4. Limitations of the Adoption Method a. The prenatal environment provided by the biological mother can also influence how the adopted child turns out b. Adoption agencies may place children in similar homes to those they were adopted from, which may affect study results c. Adoptive homes tend to be above-average environments, possibly underestimating the effects of broader environmental influences 5. Complex Family Studies a. Family studies now include various sibling types with different degrees of genetic similarity (e,g,. Identical twins, fraternal twins, full siblings, half siblings, and stepsiblings) b. Researchers measure siblings’ environments to assess their similarities and differences c. Longitudinal studies of twins and other relative assess the contributions of genes and environment to changes in traits over time Estimating Influences 1. Behavioral Geneticists and Statistical Calculations a. Researches estimate the degree to which heredity and environment account for individual differences in traits b. Concordance rates are used to measure traits that a person either has or does not have, such as a smoking habit or diabetes  c. Higher concordance rates for genetically related pairs suggests that a trait is heritable 2. Schizophrenia as an Example of Heredity a. Concordance rates for schizophrenia are 48% for identical twins and 17% for fraternal twins b. Schizophrenia is estimated to have a heritability of 80% or higher c. Children with a parent who has schizophrenia face a higher risk, even if adopted away d. The odds of an identical twin developing schizophrenia are around 50%, meaning that environmental factors also contribute 3. Environmental Contributions to Schizophrenia a. Children at genetic risk are more likely to develop schizophrenia if exposed to certain environmental factors (e.g., mental illness or delivery complications 4. Correlation Coefficients for Traits with Varying Degrees a. Correlations, not concordance rates, are used for traits present in varying degrees (e.g., height or intelligence) b. Behavioral genetics studies measure how similar pairs of individuals are in traits like IQ 5. Twin Study of Angry Emotionality a. Robert Plomin and colleagues studied the heritability of angry emotionality in twins b. Identical and fraternal twins raised together or apart were tested for correlations in emotionality  6. Evidence of Genetic Influence (Heritability) a. Identical twins are more similar in angry emotionality than fraternal twins b. A correlation of 0.33 for identical twins raised apart indicates the role of genetic makeup c. Around a third of the variation in emotionality can be linked to genetic differences 7. Shared Environmental Influences a. Twins raised together are slightly more similar than those raised apart, indicating shared environmental influences b. Shared influences are weak, as twins are almost as similar when raised apart as when raised together 8. Nonshared Environmental Influences a. Nonshared experiences unique to individuals (e.g., different life events or treatments) make family members different b. The correlation of 0,37 for identical twins raised together shows nonshared environmental influences at work Molecular Genetics 1. Behavioral Genetics Limitations a. Behavioral genetics studies do not identify which genes are responsible for heritable traits b. The Human Genome Project enabled new approaches to studying genetic and environmental influences 2. Molecular Genetics a. Molecular genetics identifies and analyzes specific genes and their effects  b. Researchers can compare individuals with certain gene variants to those without c. The effects of specific genes can be studied in combinations with environmental factors 3. Genome-Wide Association Studies a. Researchers can analyze participants’ entire genomes through cheek swabs b. Genome-wide associated studies help identify genes that contribute to polygenic traits c. Molecular genetics aims to quantify the contribution of specific genes to variation in traits 4. Challenges in Identifying Genes for Psychological Traits a. Large numbers of genes contribute to polygenic traits, with each having a small effect b. Studies with large samples (e.g., 100,000 people) are needed to detect these small effects c. Calculating “risk gene” scores can help predict the likelihood of developing a trait or disorder 5. APOE E4 and Alzheimer’s Disease a. APEO E4 is a gene variant linked to a higher risk of Alzheimer’s disease b. Having two APOE E4 genes increases an individual’s Alzheimer’s risk from 10% to 80% c. APOE E4 combined with environmental risk factors, like traumatic brain injury, further increases the odds of developing Azheimer’s 6. Contributions of Behavioral and Molecular Genetics  a. Behavioral genetics has revealed much about heritability, shared, and nonshared environments b. Molecular genetics is helping to identify specific genes and their interactions with environmental factors 2.4 The Heritability of Genes 1. Impact of Behavioral Genetics Studies on Human Development Understanding a. Studies reveal genetic contributions to individual differences in all human traits b. No traits are 0% or 100% heritable; environment matters too 2. Findings on Heritability of Traits a. Meta-analysis (Polderman et al., 2015) findings i. Heritability of human traits averages 50% ii. Genes and environment equally contribute to human variation 3. Twin Study Findings a. Correlations between identical twin pairs are double those of fraternal twins b. Role of shared and nonshared environments i. Shared environment: important for some traits (e.g., conduct problems , religiosity ii. Nonshared environment: more crucial for individual 4. Minnesota Study of Twins Reared Apart a. Figure 2.4 correlations between traits of identical twins raised apart b. Research samples on physical, intellectual, and personality traits of twins Physical and Psychological Traits 1. Genetic Influence on Observable Physical Characteristics  a. Strong association between genetics and traits like eye color and height b. Body weight is heritable 2. Evidence of Genetic Influence on Weight a. Adopted children resemble biological parents in weight, not adoptive parents b. Study by Grilo & Pogue-Geile (1991) supporting genetic influence 3. Genetic Influence on Psychological Traits a. Brain activity patterns and alcohol reaction are highly heritable b. Supporting studies: Lykken et al. (1982), Neale & Martin (1989) 4. Genetic Contribution to Aging and Physical Functioning in Older Adults a. Genetic differences contribute as much as environmental ones to aging b. Genes account for 35-40% of variation and longevity c. Study by Finkel et al. (2014, 2017) on genetic and chronic diseases Intellectual Abilities 1. Genetic Influence on General Intelligence a. General intelligence is moderately heritable, with genes accounting for about 50% of IQ variation b. Heritability of special mental abilities and academic achievement 2. Correlations in IQ Between Relatives a. Higher correlations in IQ scores of genetically related individuals b. Identical twins show highest IQ correlations, especially when raised together 3. Environmental Influence on IQ a. Family members reared together have more similar IQs than those reared apart b. Fraternal twins more alike in IQ than non-twin siblings  c. Some correlation between adoptive parents and children (lower than biological) 4. Influence of Genes and Environment Over the Lifespan a. Genetic influence on IQ increases from infancy to adulthood b. Heritability rises to 70% by adolescence and even higher in adulthood c. Nonshared environmental influences become more important with age 5. Socioeconomic Status (SES) and Heritability of IQ a. Higher SES children show stronger genetic influence on IQ (72%) b. Low SES children show stronger environmental influence on IQ 6. Environmental Enrichment and Intellectual Development a. Enriching environments can significantly improve children’s IQs b. Adopted children show higher IQs when placed in intellectually stimulating homes c. Environmental interventions can positively a;ter genetically influenced traits Temperament and Personality 1. Heritability of Temperament and Personality a. Genes contribute to individual differences in both temperament and personality b. Correlations for identical twin infants’ temperament range from 0.50 to 0.60 c. Fraternal twins share almost zero correlations in temperament 2. Influence of Family Environment on Temperament a. Shared environment does little to make siblings similar in temperament and personality b. Nonshared environmental factors are more influential than shared family environment  3. Genetic Influence on Adult Personality a. About 40% of the variation in adult personality traits is attributable to genetics b. Only 5% of personality variation is influenced by shared family environment c. Nonshared environmental influences explain 55% of adult personality variability 4. Heritability of Psychological Disorders a. Many psychological disorders, like anxiety and depression, are moderately heritable b. The degree of heritability varies between different psychological conditions 5. Heritability of Attitudes and Interest a. Genetic differences modestly contribute to attitudes and interests, including religiousness, political views, and vocational interests 6. Challenges in Identifying Specific Genes a. It is difficult to pinpoint specific genes responsible for polygenic traits b. The complexity of how genes contribute to heritable traits is not fully understood 2.5 Gene-Environment Interplay 1. Gene Activity Throughout Life a. Genes continually “turn on” and “turn off” throughout the lifespan b. Ever-changing environmental influences also affect development from conception to death 2. Relationship Between Genes and Environment a. Genes and environment are closely interrelated b. Behavioral geneticists aim to determine how much variation in traits like intelligence is due to genetic makeup vs. experience  3. Limitations of Behavioral Genetics Research a. While useful, behavioral genetics provides limited insight to the complex interplay between genes and environment 4. Forms of Gene-Environment Interplay a. Gene-environment interactions: heredity and environment work together to shape human traits b. Gene-environment correlations: genetic makeup influences the experiences individuals have c. Epigenetic effects on gene expression: environmental factors can affect how genes are expressed Gene-Environment Interactions 1. Gene-Environment Interaction: Example of 5-HTTLPR Gene a. Avshalom Caspi’s study (2003) explored why stressful life experiences cause depression and some but not others b. DNA analysis on New Zealanders identified variants of the 5-HTTLPR gene, which affects serotonin levels linked to stress and depression in some but not others 2. Study Design and Results a. Surveys measured stressful events experienced between ages 21-26 b. At age 26, researchers assess whether participants had experienced depression c. Results showed individuals with two high-risk 5-HTTPLR variants were more vulnerable to depression when exposed to multiple stressful events  d. Those with protective gene variants were less likely to become depressed, even with multiple stressors 3. Implications of the Findings a. Genes affect depression risk only under stressful; environments b. Stressful environments only trigger depression in individuals predisposed by genetics 4. Broader Implications of 5-HTTLPR Gene a. Both human and animal studies link 5-HTTLPR to stress reactivity and psychological disorders b. Risky gene variants make individuals more vulnerable to emotional problems, such as in cases of bullying c. Some studies (Culverhouse et al., 2018) have failed to replicate these gene-environment interactions, highlighting challenges in determining gene effects The Diathesis-Stress Model 1. Diathesis-Stress Model of Psychology a. Overview of the diathesis-stress model b. Components of the model i. Definition of diathesis (predisposition or vulnerability) ii. Definition of stress (environmental triggers or experiences) c. Interaction between genetic and environmental factors i. Role of high-risk genes ii. Impact of high-risk environments or stressful experiences  d. Mechanism of psychological disorder development i. How the combination of diathesis and stress leads to psychological disorders ii. Examples of psychological disorders resulting from this interaction e. Implications for mental health i. Importance of understanding individual vulnerability ii. Role of early intervention and support 2. Application of Genetic Knowledge in Preventing Psychological Problems a. Importance of identifying high risk individuals i. Potential to prevent psychological problems more effectively ii. Role of genetic predispositions in psychological vulnerability b. Case Study: Gene Brody’s Research on African-American Youth (2009) i. Focus on low-income, African American 11-year-olds ii. High-risk versions of 5-HTTLPR genes and behavioral outcomes c. Prevention program for high-risk youth i. Program elements: good parenting skills and parent-child communication ii. Impact on preventing substance use and early sexual intercourse d. Effectiveness of the prevention program i. Consumption between youth with high-risk genes in the program and the control group ii. Outcome: control group with high-risk genes engaged in problem behaviors at twice the rate e. Evidence of gene-environment interaction  i. Role of 5-HTTLPR gene and other genes affecting neurotransmitter activity ii. Use of molecular genetics approach to study interactions between specific genes and experiences 3. Beyond the Diathesis-Stress Model a. Introduction of new findings i. The diathesis-stress model may only explain part of the story The Differential Susceptibility Model 1. Reevaluation of “Risk Genes” as “Plasticity Genes” a. Initial Labeling of Risk Genes i. Genes like 5-HTTLPR were initially labeled as “risk genes” for depression and antisocial behavior b. New understanding of plasticity genes i. These genes allow individuals to benefit more from positive environments ii. Individuals with these genes show more problems in stressful environments but excel in nurturing ones 2. Differential Susceptibility Hypothesis a. Definition: some individuals are more reactive to environmental influences, both positive and negative b. Orchid vs. Dandelion Metaphor i. “Orchids” thrive in optimal conditions but wilt in poor environments ii. “Dandelions” grow well in almost any condition 3. Belsky and Beaver’s Study on Self Control (2011)  a. Study focus i. Examine 5 gene variants (including 5-HTTLPR) in 11th-grade students ii. Assessed maternal support and involvement iii. Measured teens’ self-regulation and self-control b. Findings i. Males with many “plasticity” genes had high self-control with supportive mothers but low self-control with unsupportive mothers ii. No differential susceptibility effect observed in females iii. Boys with fewer “plasticity” genes (dandelions) showed no correlation between self-control and maternal support 4. Implications for Interventions a. Combining Diathesis-Stress and Differential Susceptibility Models i. “Risk” genes may also help individuals excel in supportive environments b. Targeting at-risk children i. Interventions like positive parenting may benefit children with plasticity genes ii. Lemery-Chalfant et al. (2018) showed children with high environmental; susceptibility genes benefited more from family interventions iii. Potential for “orchid” children to thrive with proper care Gene-Environment Correlations 1. Gene-Environment Correlations a. Definition: people’s genes and their experiences are interrelated (Scarr & McCartney, 1983)  i. Builds on theorizing by Robert Plomin and colleagues (1977) b. Contrast with gene-environment interactions i. Gene-environment interactions: people with different genes react differently to similar situations ii. Gene-environment correlations: people with different genes have different experiences (Loehlin, 1992) 2. Types of Gene-Environment Correlations a. Passive gene-environment correlations i. Environment is provided by biological parents, reflecting their own genetic predispositions ii. Example: sociable parents provide an environment that nurtures sociable tendencies in their children b. Evocative gene-environment correlations i. A child’s genetically influenced traits evoke certain responses from others ii. Example: a sociable child may receive more interaction from adults and peers than a shy child c. Active Gene-Environment Correlations i. Individuals seek environments that are compatible with their genetic tendencies ii. Example: a sociable child might seek out more sociable situations, while a shy child might avoid them 3. Illustration of Gene-Environment Correlations a. Sociable vs. sh children  i. Children with genes for sociability likely seek and create more social environments ii. Shy children might have more solitary experiences due to both their genes and their environment Passive Gene-Environment Correlations 1. Passive Gene-Environment Correlations a. Definition: parents pass on both their genes and create a home environment that matches those genes b. How it works: the home environment parents provide reinforce inherited genes c. Example: i. Sociable parents give their children sociable genes ii. They also create a social environment (hosting gatherings, chatting at dinner) iii. This makes the child more sociable than they might have been otherwise d. Contrast example: i. Shy parents give their children genes for shyness ii. They create a less social environment iii. This may make the child less sociable due to both genes and environment Evocative Gene-Environment Correlations 1. Evocative Gene-Environment Correlations a. Definition: a child’s genes can cause specific reactions from others b. Examples: i. A sociable baby gets more smiles, hugs, and social interactions  ii. A shy baby might get less social attention because others may be unsure how to engage 2. Impact on Development a. Sociable children: i. They are more likely to be chosen as playmates ii. They receive more invitations to parties during adolescence iii. They have more opportunities for customer service roles as adults b. Conclusion: genetic traits can shape how others interact with an individual, affecting their social environment throughout life Active Gene-Environment Correlations 1. Active Gene-Environment Correlations a. Definition i. Children’s genotypes influence the environments they seek and create b. Examples i. An individual with a genetic predisposition for extraversion is likely to: 1. Seek out friends 2. Attend parties 3. Join organizations 4. Collect friends on social media 5. Build a socially stimulating niche that enhances social skills ii. A child with genes for shyness may: 1. Avoid large group activities 2. Develop solitary interests  c. Developmental Influence i. As people grow, they become better at building their own environments ii. Active gene-environment correlations become more significant over time d. Conclusion i. By choosing and creating their own environments, individuals play an active role in their development Implications of Gene-Environment Correlations 1. Implications of Gene-Environment Correlation a. Many environmental measures are heritable b. Identical twins are more similar than fraternal twins in the environments they experience and their perceptions of those environments c. Genetic makeup related to various environmental influences: i. Parenting aspects, like warmth and quality of parent-child relationships ii. Time spent watching television iii. Number of stressful life events experienced iv. Likelihood of divorce d. Example: Identical twins who are irritable might create a hostiles family environment, while calm twins might foster a warm family setting e. Robert Plomin (2018) states that measure believed to assess only environmental influences have an average heritability of about 25% 2. Rethinking Development Assumptions a. These findings suggest that environmental factors might actually be influenced by genetics  b. For example, parents who read to their kids might not be the only reason their kids are smarter; families with higher intelligence might just naturally seek out reading more c. Experiments matter: research shows reading really does help kids with language skills 3. Proof of Gene-Environment Connections a. David Reiss and his team (2000) found that genes shared between parents and teens can influence how family experiences affect development b. Negative parenting styles are linked to teens behaving badly, partly because of shared genes c. Parent-child relationships can be a two-way street: i. Tough parenting can lead to trouble for their kids ii. Kids with antisocial tendencies might provoke their parents into negative behavior 4. The Need for Studies that Consider Genetics a. Simple studies can’t really show if experiences impact development b. We need more research that takes genetics into account c. Ways to do this: i. Look at how adoptive kids are affected by their environment without genetic similarities ii. Study identical twins to see if their differences come from different experiences  d. For example, twins who get more negative disciple at age 7 are likely to have more behavior issues by age 12 Epigenetic Effects on Gene Expression 1. Understanding epigenetic effects a. Epigenetic effects can show how the environment can influence how specific genes work b. Environmental factors such as diet, stress, drugs, toxins, and parental care can add chemical codes on genes, affecting whether they are active or inactive c. These effects can create an “epigenome” alongside the genome, which helps determine how genes express themselves without actually changing them d. Changes in gene expression can influence cognition, emotion, behavior, and health over a person’s lifetime e. Epigenetic markings can lead to long-lasting developmental patterns or enable change, showing developmental plasticity 2. Importance of Epigenetics in Early Development a. Epigenetics is crucial during prenatal development, with environmental factors guiding growth b. Maternal stress can cause DNA methylation, turning off stress-related genes and impacting the child’s stress response 3. Ongoing Epigenetic Changes Throughout Life a. Epigenetic changes continue throughout life; for example, social stress tests can increase DNA methylation b. Learning can trigger epigenetic changes in brain-related genes  4. Key Discoveries in Epigenetics Research a. Study of identical twins: i. Astronaut Scott Kelly and his twin Mark participated in a NASA study ii. Scott spent nearly a year in space, legging to unique physiological changes not seen in Mark iii. He experienced changes in gene expression due to the zero-gravity environment iv. Most changes reversed quickly after returning to Earth, but some persisted for months, affecting his health Epigenetic effects and Differences Between Identical Twins 1. Epigenetic effects in identical twins a. epigenetic effects may explain why identical twins, despite having the same genes, often differ b. Differences in epigenetic markings can be seen at birth, indicating that prenatal experiences shape their development c. As twins age, their genetic marks become more distinct 2. study by Mario Fraga and his colleagues (2005) a. the study analyzed in DNA and RNA from 40 pairs of identical twins Age 3 to 74 b. in 3-year-old twins, gene expression patterns were very similar; if one twins Jean was active, the others was too c. in contrast, 50-year-old twins showed significant differences in gene expression; mini jeans active in one twin were inactive in the other 3. influence in lifestyle on gene expression  a. adult twins who led different lifestyles ( diet, physical activity, substance use) had greater differences in gene expression than those who lived similarly b. genetic makeup influences experiences, leading to more similar epigenetic patterns and identical twins compared to fraternal twins c. unique experiences change how genes function, contributing to differences between identical twins Epigenetic effects of early parenting 1. Epigenetic effects of early caregiving in Rat pups a. Michael Meaney, Francis Champagne, and colleagues studied how early caregiving affects rat pup's gene activity and development b. Nurturant mother rats, who lick and groom their pups, raised pups that handle stress well c. Neglectful mothers, who do not provide tactile care, raise pups that are timid and easily stressed 2. Nature vs. Nurture and Stress Reactivity a. Rearing, not heredity, determined stress reactivity and pups b. Pups raised by nurturant mothers were stress resistant, even if born to neglectful mothers c. Pups raised by neglectful mothers were stress reactive, even if born to nurturing mothers 3. Epigenetic Effects on Gene Expression a. Nurtured pups had gene and the hippocampus that stayed active, helping regulate stress hormones  b. In neglected pups, these jeans were turned off by DNA methylation, impairing their ability to handle stress c. Early caregiving affected gene expression, leading to lasting effects on development 4. Transmission of Parenting Styles a. Daughters of neglectful mothers grew up to being neglectful mothers due to changes in genes affecting sensitivity to female hormones b. This is an example of epigenetic transmission of caregiving styles from one generation to the next 5. Epigenetic Influence Beyond Genetic Inheritance a. Epigenetic effects show a new way parents influence children beyond genetics and social learning: by influencing gene expression b. In humans, studies suggest similar effects. non-breasted infants had more DNA methylation in stronger stress responses during interactions with their mothers 6. Human and Animal Studies a. DNA methylation may explain the transmission of abusive or neglectful parenting from mother to daughter and humans and monkeys b. It also links early-life stress to mental health problems later in life Intergenerational Transmission of Epigenetic Effects 1. Intergenerational Epigenetic Effects in Animals a. Research shows that a parent's life experiences can affect their descendants across multiple generations  b. An experiment with mice conditioned to fear a cherry blossom odor showed that the fear was passed on to their offspring, even though the offspring never encountered the odor before c. The fear response was transmitted through methylation of a gene in the father's sperm, which was passed to the grandchildren d. Fathers were used to avoid the direct transmission of fear from mothers to their offspring 2. Intergenerational Epigenetic Effects in Humans a. Although not conclusively proven in humans, epigenetic changes have been observed in trauma victims b. Holocaust survivors, abuse victims, and others may pass biological traces of trauma to their descendants c. however, most epigenetic marks on sperm and eggs are erased after conception (Moore, 2015), so it's not guaranteed that stress will be passed down d. Epigenetic marks can sometimes be reversed through certain drugs or nurturing environments 3. Potential for Reversing Epigenetic Effects a. Conditioning techniques or drugs reversed the fear response in father mice, erasing the epigenetic marks that caused it 4. Where Epigenetic Research is Heading a. The full extent of how often and how much environmentally caused epigenetic effects contribute to development or are passed down is still unknown b. It's clear that experiences can influence gene expression and behavior  c. We are learning how genes and environments work together in development 5. Types of Gene-Environment Interplay a. Gene-environment interaction: people with different genes are affected differently by environmental influences (for example, stress leading to depression in those with high risk genes) b. Gene environment correlation: people with different genes experience different environments, often influence by their own genetics (for example, sociable children seek sociable environments) c. Epigenetic effects environmental factors: alter gene expression, and some epigenetic changes can be passed to offspring (for example, abuse causing an overactive stress response system) Controversies Surrounding Genetic Research 1. Challenges of Genetic Advances a. Geneticists now have the ability to identify carriers in future victims of diseases, customize treatments, provide information to parents, an alter genes through gene therapy b. Gene therapies have had some success treating disorders like hemophilia, cystic fibrosis, and sickle cell disease c. CRISPR Technology is revolutionizing gene therapy by editing the genome and inserting functioning genes 2. limitations and Ethical Concerns a. Gene therapies may help with single gene pair disorders, but most conditions involve multiple genes and environmental factors, making treatment complex  b. Success requires delivering genes to the right parts of the body, controlling when they turn on or off, and managing environmental influences c. ethical concerns and failed experiments highlight the complexity and risks 3. Future Genetic Therapies a. Techniques for genetic diagnosis and therapy will continue to improve b. Researchers are working on drugs and dietary treatments to change epigenetic codings linked to health issues c. Society will need to make decisions on how to use these technologies responsibly 4. Advice for Parents a. Parents should understand their children's genetic predispositions and help them explore their interests and strengths rather than trying to change them b. Promoting optimal experiences for children involves knowing which environments promote healthy development