Podcast
Questions and Answers
What is the main reason for the overlap between behavioural genetics and personality psychology?
Which approach in behavioural genetics uses DNA samples to measure genetic variation?
What distinguishes the classic approach from the modern approach in behavioural genetics?
What is the primary focus of the classic approach in behavioural genetics?
Signup and view all the answers
Which type of studies are still relevant for the study of traits like the Big Five?
Signup and view all the answers
What makes it possible to correlate observed differences in participants' genes with their traits in molecular genetics?
Signup and view all the answers
What does the modern approach in behavioural genetics use to measure genetic variation?
Signup and view all the answers
What is the nature versus nurture debate about?
Signup and view all the answers
What does the blank slate model propose?
Signup and view all the answers
What is the topic of clinical or forensic psychology in relation to inherited dispositions?
Signup and view all the answers
What is the focus of research in behavioral genetics?
Signup and view all the answers
What does the blank slate model not deny about personality?
Signup and view all the answers
What do evolutionary theories suggest about personality traits?
Signup and view all the answers
What is the focus of clinical or forensic psychology regarding personality traits?
Signup and view all the answers
What does a heritability coefficient of 0% indicate?
Signup and view all the answers
What is the name for the causal effect of genes on the phenotype?
Signup and view all the answers
What does h2 represent in the context of heritability coefficient?
Signup and view all the answers
Why is it important to specify the population of a study in behavioral genetics?
Signup and view all the answers
What does a heritability coefficient of 100% indicate?
Signup and view all the answers
What reflects the influence of genes that are inherited from parents?
Signup and view all the answers
What does '1-$h^2$' represent in the context of heritability coefficient?
Signup and view all the answers
Why do heritability coefficients depend on the population in which they are estimated?
Signup and view all the answers
What does 'h' reflect in terms of genetic influence?
Signup and view all the answers
What does '1-h' represent in relation to genetic and environmental influences?
Signup and view all the answers
Why might some people believe that heritability coefficients are meaningless?
Signup and view all the answers
What is the term used by personality psychologists to refer to specific observable attributes?
Signup and view all the answers
What do behavioural geneticists call specific observable attributes?
Signup and view all the answers
What is the information encoded in an individual's DNA known as?
Signup and view all the answers
What are variations in the genome that can produce differences in humans' phenotypes called?
Signup and view all the answers
What do genes come in different versions known as?
Signup and view all the answers
What is the focus of environmental factors in behavioural genetics?
Signup and view all the answers
What does the classic approach in behavioural genetics not measure directly?
Signup and view all the answers
What can sometimes be responsible for a phenotype?
Signup and view all the answers
What are variations in many genes that contribute to variation in a phenotype called?
Signup and view all the answers
What does the heritability coefficient measure?
Signup and view all the answers
What does the classic twin design aim to separate the influence of?
Signup and view all the answers
How is the heritability coefficient computed using twin correlations?
Signup and view all the answers
What does a correlation of $r = .87$ for height in MZ twins suggest?
Signup and view all the answers
What is a key limitation of twin studies mentioned in the text?
Signup and view all the answers
What does the causal model in Figure 8.2 explain?
Signup and view all the answers
What does a correlation of $r = .48$ for personality traits in MZ twins suggest?
Signup and view all the answers
What does 'no assortative mating' mean in the context of twin studies?
Signup and view all the answers
What does 'equal shared environments for MZ and DZ twins' mean in the classic twin design?
Signup and view all the answers
What reflects the difference in genetic similarity between MZ and DZ twins?
Signup and view all the answers
What percentage of height heritability is estimated from the given information?
Signup and view all the answers
What does the estimate of 3% due to shared environmental factors indicate?
Signup and view all the answers
What does the estimate of 7% due to non-shared environmental factors show?
Signup and view all the answers
What does the relatively small variance in access to protein-rich foods in North America imply?
Signup and view all the answers
What is the total variance in height separated into, based on the given information?
Signup and view all the answers
What do the estimates derived from MZ twins growing up apart and the given calculations suggest about the influence of shared environment on height?
Signup and view all the answers
What do the estimates obtained from MZ twins growing up apart and the given calculations indicate about the influence of non-shared environment on making twins dissimilar?
Signup and view all the answers
What do the given estimates suggest about the impact of nutrition on height variation?
Signup and view all the answers
How are genetic, shared environmental, and non-shared environmental factors contributing to the total variance in height?
Signup and view all the answers
What is the genetic similarity between dizygotic twins (DZ)?
Signup and view all the answers
Why are dizygotic twins (DZ) more similar to monozygotic twins (MZ) than normal siblings?
Signup and view all the answers
What is the main reason for comparing monozygotic (MZ) twins to dizygotic (DZ) twins rather than to siblings?
Signup and view all the answers
What is the biggest challenge in twin studies?
Signup and view all the answers
Why are dizygotic twins (DZ) genetically not different from normal siblings?
Signup and view all the answers
What percentage of genes do children inherit from each parent?
Signup and view all the answers
What is the result of a split of the same fertilized egg during the early stages of development of a fetus?
Signup and view all the answers
What do dizygotic twins (DZ) result from?
Signup and view all the answers
What makes it possible for behavioural geneticists to compare MZ and DZ twins?
Signup and view all the answers
Why are monozygotic (MZ) twins genetically identical?
Signup and view all the answers
What percentage of the variance in handedness is inherited?
Signup and view all the answers
What term would be more appropriate instead of 'unshared environment' in twins?
Signup and view all the answers
What does the finding about married MZ twins' happiness suggest?
Signup and view all the answers
What do the results of the study comparing life-satisfaction in MZ twin pairs demonstrate?
Signup and view all the answers
What does the text suggest about the influence of environmental factors on handedness?
Signup and view all the answers
What is the likely cause of left-handedness according to the text?
Signup and view all the answers
What type of environmental factors can influence adult twins' differences?
Signup and view all the answers
What does the text suggest about the term 'unshared environment' when studying traits in twins?
Signup and view all the answers
What does the study comparing life-satisfaction in MZ twin pairs illustrate about environmental influences?
Signup and view all the answers
What does the text imply about the causes of left-handedness?
Signup and view all the answers
What did a rare adoption study of personality traits related to the Big Five find?
Signup and view all the answers
What did the adoption study find about the shared environment effect on personality traits?
Signup and view all the answers
What do results from the adoption study suggest about the variance in personality traits?
Signup and view all the answers
What did studies using a multi-method approach find about unshared environmental variance in twin studies?
Signup and view all the answers
What is an example of unshared biological development mentioned in the text?
Signup and view all the answers
'Handedness' could be influenced by recessive genes, similar to which other trait?
Signup and view all the answers
What do unshared environmental factors in twin studies primarily represent?
Signup and view all the answers
What does understanding the influence of shared and unshared environment on personality traits require?
Signup and view all the answers
What does the development of a human adult from an embryo to an adult lead to?
Signup and view all the answers
What does measurement error in classic twin studies tend to do?
Signup and view all the answers
What does the pattern of MZ and DZ twin correlations suggest about the heritability of personality?
Signup and view all the answers
What does the lack of shared environmental factors influencing personality mean for parental influence?
Signup and view all the answers
Why might some parents find it surprising that their parenting styles do not produce similar outcomes in their children's personalities?
Signup and view all the answers
What was particularly unwelcome among developmental psychologists regarding the influence of parenting styles on child development?
Signup and view all the answers
What do many parents believe about shaping their children's personality, especially with their first child?
Signup and view all the answers
What did the lack of shared environmental factors influencing personality mean for the shared environment?
Signup and view all the answers
Why might some parents learn from experience that their influence is rather limited when they have a second child?
Signup and view all the answers
What is the primary reason for MZ twins correlations to exceed two times the DZ correlations?
Signup and view all the answers
Why does the standard formula for heritability estimation not work for phenotypes like eye color?
Signup and view all the answers
What do DZ correlations less than half of MZ correlations suggest about personality traits?
Signup and view all the answers
Why are shared environment effects on personality considered minimal?
Signup and view all the answers
What does the decreasing influence of shared environment over time imply?
Signup and view all the answers
What is the consensus about the percentage of personality trait variance caused by genetic differences?
Signup and view all the answers
What do adoption studies and studies of children with different biological parents in the same household provide rare insights into?
Signup and view all the answers
What reflects parents' early influence on personality but does not last into adulthood?
Signup and view all the answers
What phenotypes do parents have a lasting influence on into early adulthood, indicating the impact of shared environment?
Signup and view all the answers
What does behavior genetics research emphasize about parenting's role in children's personalities?
Signup and view all the answers
What does an additive model in genetics assume?
Signup and view all the answers
What does the example of eye color inheritance illustrate?
Signup and view all the answers
What does 'gene by gene interaction' refer to?
Signup and view all the answers
What is the problem with the simple additive model in genetics?
Signup and view all the answers
In the context of genetics, what does 'non-additive effects' refer to?
Signup and view all the answers
What is the primary difference between gene-environment correlations and personality-situation correlations?
Signup and view all the answers
What does the '10,000 hours to gain expertise' idea suggest about skill development?
Signup and view all the answers
What does the case of the Williams sisters illustrate about skill development?
Signup and view all the answers
What does the concept of gene-environment correlations imply about the influence of genetic dispositions on individual interests?
Signup and view all the answers
What does the 10,000 hours rule fail to account for in terms of skill development?
Signup and view all the answers
What does the case of the author's guitar and Badminton experiences suggest about gene-environment correlations?
Signup and view all the answers
What does the case of the author's guitar and Badminton experiences suggest about the influence of environmental factors on individual interests?
Signup and view all the answers
What was the best-known demonstration of the impact of inherited diseases according to the text?
Signup and view all the answers
What is a common misunderstanding about genetic factors in behavioral genetics, as mentioned in the text?
Signup and view all the answers
What did the finding that sexual orientation is partially inherited lead to, as mentioned in the text?
Signup and view all the answers
What did the use of heritability as a progressive argument for gay and lesbian rights demonstrate, according to the text?
Signup and view all the answers
What was a problem with evidence of inherited dispositions when homosexuality was viewed as a disorder?
Signup and view all the answers
What do individuals who believe that sexual orientation is innate tend to support, according to the text?
Signup and view all the answers
What does the text imply about politics and values in arguments about heritability?
Signup and view all the answers
What was a relevant outcome of discovering Phenylketonuria (PKU), according to the text?
Signup and view all the answers
What does the text suggest about using heritability as an argument for societal change?
Signup and view all the answers
What is a common misconception about heritability coefficients?
Signup and view all the answers
What does the study of adolescent twins' musical abilities show about gene-environment correlations?
Signup and view all the answers
What does the text suggest about the impact of genes and environment on musical abilities?
Signup and view all the answers
What is crucial for understanding skills and abilities according to the text?
Signup and view all the answers
How can environmental effects be demonstrated for traits with high heritability?
Signup and view all the answers
What did lifestyle changes demonstrate about environmental factors and heritability coefficients?
Signup and view all the answers
What did the review article from 2021 show about the variance genetic profiles could explain in a large number of phenotypes/characteristics?
Signup and view all the answers
What did the genetic profiles explain about personality traits like extraversion and neuroticism?
Signup and view all the answers
What did the text reveal about the effect size for drug use?
Signup and view all the answers
What did the molecular genetics studies reveal about genes contributing to human diversity?
Signup and view all the answers
What did the second finding indicate about molecular genetics studies and twin studies?
Signup and view all the answers
What did the text suggest about finding genetic predictors of important personality traits and life outcomes?
Signup and view all the answers
What did the text reveal about genetic profiles' ability to explain characteristics like happiness/life satisfaction, age of first intercourse, and number of children?
Signup and view all the answers
What did a review article from 2021 demonstrate about genetic predictors' ability to explain homosexuality?
Signup and view all the answers
Study Notes
Twin Studies and Heritability
- Behavioral geneticists use twin studies to separate genetic and environmental influences on traits.
- Adoption studies with MZ twins show that the correlation between phenotypes can be interpreted as the heritability coefficient.
- The causal model in Figure 8.2 explains the observed correlation between twins' phenotypes.
- A study of MZ twins who grew up apart showed a correlation of r =.87 for height, suggesting 87% heritability.
- The same study found an average correlation of r =.5 for personality traits, suggesting 50% heritability.
- A key limitation of the study is the rarity of twins and adoptions, and the inability to replicate results.
- The classic twin design compares the similarity between MZ and DZ twins raised together.
- The design aims to separate the influence of genes and shared environment, assuming equal shared environments for MZ and DZ twins.
- Assumptions include no assortative mating and that genetic similarity of DZ twins is half of MZ twins.
- The classic twin design uses a causal model to estimate heritability and shared environment influence.
- A study found a correlation of r =.93 for MZ twins’ height and r =.48 for DZ twins’ height, illustrating the classic twin design.
- The heritability coefficient can be computed by subtracting the DZ correlation from the MZ correlation.
Influence of Parents on Children's Personality Traits
- Parents may try to influence their children's personality traits, such as politeness, hard work, and outgoing nature, but this influence may be limited.
- Adoption studies, which avoid genetic similarity between parents and children, are essential for understanding the influence of shared environment on personality traits.
- A rare adoption study of personality traits related to the Big Five found that the shared environment may contribute to adolescents' personalities.
- The strongest shared environment effect in the adoption study was found for a scale called "Traditionalism," linked to the Liberalism facet of Openness to Experience.
- Results from the adoption study suggest that genes explain 40% of the variance in personality traits, while the shared environment explains 20%.
- Measurement error in classic twin studies may underestimate the similarity of twins' personalities and underestimate heritability.
- Studies using a multi-method approach found that some of the unshared environmental variance in twin studies could be measurement error, leading to increased heritability estimates.
- Unshared environmental factors in twin studies may not be identifiable and could be random processes that occur during human development.
- The development of a human adult from an embryo to an adult is complex, leading to differences in individuals despite starting with the same DNA.
- Handedness is an example of unshared biological development, with about 10% of the population being left-handed, which is not actively influenced by parents.
- Handedness could be influenced by recessive genes, similar to eye color, where two brown-eyed parents carrying a blue-eye allele could have a blue-eyed child with a 25% chance.
- Understanding the influence of shared and unshared environment on personality traits requires more evidence from adoption studies and a multi-method approach to measurement.
Genetic and Environmental Influences on Personality
- DZ twins are less similar in phenotypes due to dominant-recessive and interaction effects, while MZ twins have identical genes and inherit the same interaction effects.
- MZ twins correlations can exceed two times the DZ correlations due to the impact of genetic and non-additive genetic influences.
- The standard formula for heritability estimation does not work for phenotypes like eye color due to limitations on explained variance.
- Some personality traits show DZ correlations less than half of MZ correlations, suggesting both additive and non-additive genetic influences.
- The consensus is that around 50% of personality trait variance is caused by genetic differences, with the remaining variance reflecting random factors.
- Shared environment effects on personality are minimal, as evidenced by the similarity of MZ twins who grew up together and apart.
- Adoption studies and studies of children with different biological parents in the same household are rare in the context of personality research.
- Parental influences on behavior are distinct from influences on personality, and parents can still influence behavior even when children are independent.
- Parents have an early influence on personality, but this influence does not last into adulthood, as seen in decreasing MZ and DZ correlations with age.
- Parents have a lasting influence on some phenotypes, such as religiosity, into early adulthood, indicating the impact of shared environment.
- The decreasing influence of shared environment over time implies decreasing similarity among twins or siblings in religiosity.
- Behavior genetics research changes the perception of parenting by emphasizing the role of parents in providing a supportive environment for children's unique personalities.
Expertise, Gene-Environment Correlations, and Misconceptions about Heritability
- The 10,000-hour rule for expertise suggests that passion and motivation to invest time in an activity are crucial to achieving expertise.
- Personal experience in academic psychology highlights the importance of passion and investment of time in developing expertise.
- Success in life often stems from finding and pursuing one's passion, allowing individuals to overcome obstacles and invest time in their chosen field.
- Environmental predictors for personality traits like the Big Five are not reliable, making it challenging to study gene-environment correlations for personality traits.
- A study of adolescent twins' musical abilities shows gene-environment correlations, with practice time as the environmental variable.
- Genetic variance accounts for 37% of the variance in practice times, and shared environment explains 44% of the variance, indicating the influence of both genes and environment.
- Practice times moderately affect musical abilities, with genetic factors explaining 20% of the variance, slightly stronger than the effect of practice.
- Shared environmental factors, including parental influences, play a significant role in influencing practice times and abilities.
- Gene-environment correlations are crucial for understanding skills and abilities, emphasizing the impact of opportunity and practice.
- Misconceptions about heritability include the belief that high heritability coefficients imply fixed traits, when in fact they reflect low variability in environmental factors.
- Environmental effects can be demonstrated for traits with high heritability by comparing different generations and observing changes in mean differences between generations.
- While individual variation in each generation is substantially heritable, lifestyle changes have produced notable increases in average Body-Mass-Index, demonstrating that environmental factors can influence traits despite high heritability coefficients.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge about the nature versus nurture debate, exploring the inheritance of physical and psychological traits in animals and humans. Delve into evolutionary theories and the concept of the blank slate model.