Genes and Inheritance (Behavioral Genetics) PDF
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Hamilton College
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This document discusses genes and inheritance, focusing on behavioral genetics. It explains the role of genetics in behavior and trait variation, exploring important concepts like genotype, phenotype, and concordance rates. The document also examines the interplay between nature (genes) and nurture (environment), emphasizing that both factors contribute to behavior. Furthermore, the text delves into concepts like genetic susceptibility to disorders and discusses heredity.
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enes and Inheritance (Behavioral Genetics) G Nature vs. Nurture Behavioral Genetics The role of genetics in behavior and trait variation Genes Build and modify physical aspects of the body Code and regulate protein production ...
enes and Inheritance (Behavioral Genetics) G Nature vs. Nurture Behavioral Genetics The role of genetics in behavior and trait variation Genes Build and modify physical aspects of the body Code and regulate protein production Indirectly affect behavior Behavioral Genetics: Important Terms Genotype: Set of inherited genes Phenotype: Observable traits/behaviors associated with genes and the environment Monozygotic twins: Individuals who are genetically identical Dizygotic twins: Fraternal twins, same degree of genetic similarity as any non-twin siblings Concordance rate: If one twin has a particular trait, the likelihood of the other twin having the same trait Nature vs. Nurture / Genes vs. Environment What do we mean by genes? ○ Gene = segment of a DNA molecule that forms/modifies the anatomy and physiology of the body via building/activating proteins. What do we mean by environment? ○ Everything else. For example… Prenatal environment(in the womb) Early experience Peer influence Physical features of the environment Cultural norms It’s not one or the other – it’s both! Gene BY Environment interactions A Common Misconception: Number of Genes Most of the normal variability in behavior is due to multiple genes and their interactions with the environment ○ Eye color – 6 genes ○ Skin color – 40 genes ○ Weight – 500+ genes Environments Influence Genes [epigenetics] What about Genes Influence Environments? Passive Evocative Active Genetics and Stress Genes code for the susceptibility for a particular clinical disorder (e.g., anxiety) Stress in the environment can trigger the onset of such disorders Genes code for susceptibility to the environment For those more “sensitive” to their environment, there can be both negative and positive effects Heredity Alleles ○ Genes that occupy same locus on chromosome pairs ○ Dominant genes produce effects no matter pair (hetero- or homozygous) ○ Recessive genes only produce effect with matched pair (homozygous) Autosomal recessive conditions ○ Autosomal: non-sex chromosome ○ Recessive: Carried on a recessive allele ○ With two carrier parents, 25% chance that child will have condition, 50% for carriers, 25% do not carry gene ○ e.g., cystic fibrosis, sickle cell anemia, phenylketonuria (PKU)
