Exam 3 Learning Objectives Genetics Heritability Lecture 8 1 Be able to define genome a All of our genes b Very small number of genes differ across people are made up of what a Genome Chromosomes Genes DNA 3 Be able to define behavioral genetics 2 Understand the hierarchy in the genome e g Chromosomes are made up of what Genes a To what degree are individual differences due to genetic and environmental 4 What are the controversies surrounding behavioral genetics factors a Eugenics i The study or practice of attempting to improve the human gene pool by encouraging the reproduction of people considered to have desirable traits and discouraging or preventing the reproduction of people considered to have undesirable traits b Genetic determinism i Genes and environment interact 5 What are the three major questions asked by behavioral geneticists a What causes variability in a trait genes vs environment b What environmental effects are important c How do genes and environment interact 6 What is heritability a How much an individual difference is explained by genetics 7 Be familiar with the misconceptions about heritability and be able to recognize examples a CANNOT be applied to single people i A single individual s height for example is not 10 due to their ii environment It is more accurate to say that the variation between people in height is 10 due to the environment b Is NOT constant unchangeable i Heritability only applies to a population at one point in time ii The more similar the environment between people the higher heritability will be c Is NOT a precise statistic i Only as good as the sample used 8 Be able to list and define the four methods used in behavioral genetics a Selective breeding i Can t be done ethically with humans ii Only works if a desired trait is heritable iii If selective breeding for a trait is successful the trait is at least somewhat genetic b Family studies i Correlates genetic similarity w personality similarity ii iii Problem If trait is heritable more genetic relatedness more similarity on traits 1 Families share genes and environment iv Family studies are never definitive c Twin studies i Monozygotic twins 1 Share a single fertilized egg a single zygote monozygotic 2 Share 100 of their genes ii Dizygotic twins 1 Come from two separately fertilized eggs two zygotes dizygotic 2 Share about 50 of their genes iii Monozygotic vs Dizygotic twins iv Estimate heritability 1 Are identical twins more similar than fraternal twins Yes 2 If MZ twins are more similar than DZ twins on a given trait due to heritability v Do twin studies eliminate problem from family studies vi Equal environments assumption 1 Environment experienced by identical twins no more similar than environments shared by fraternal twins d Adoption studies i Correlations on traits between adopted children and adoptive parents ii Correlations between adopted children and genetic parents genetic environmental influence influence 9 Know advantages and disadvantages associated with each method from behavioral genetics a Selective breeding i Advantages b Family studies i Advantages 1 Shows whether or not a trait is at least somewhat genetic ii Disadvantages 1 Only works if a desired trait is heritable 2 Can t be done ethically with humans 1 Correlates genetic similarity w personality similarity 1 Families share genes and environment ii Disadvantages c Twin Studies i Advantages 1 Similar genes same environment ii Disadvantages 1 Twin studies are more likely to be case studies which limit their scope and generalizability d Adoption Studies i Advantages ii Disadvantages 1 You can see if the environment influences our genes directly 1 Representativeness 2 Selective placement of adopted children 10 Know the difference between monozygotic and dizygotic twins a Monozygotic i Identical twins ii Shared placenta iii Share a single fertilized egg iv Share 100 of their genes b Dizygotic i Fraternal twins ii Separate placentas iii Come from two separately fertilized eggs iv Share about 50 of their genes dizygotic twins a Neuroticism b DZ twins correlated at 18 c MZ twins correlated at 41 d Heritability 2XDifference in correlation e Heritability 2 41 18 f Heritability 2 23 46 g Heritability 46 11 Be able to compute heritability if I give you the correlations for monozygotic and 12 Which kind of study generally gets higher heritability scores Adoption or twin studies a Twin studies 13 What is nonadditive genetic variance a The configural or interactive influence of genes on traits Nonadditive genetic variance has been invoked to explain why the ratio of trait concordance for MZ twins and DZ twins is sometimes greater than 2 0 as in the case of recent studies on extraversion 14 Be familiar with the heritability of the extraversion neuroticism drinking and alcoholism a Extraversion b Neuroticism c Drinking d Alcoholism i 40 60 heritable i 30 54 heritable i 36 56 heritable i 50 71 heritable 15 Know that any variance not accounted for by genetics is accounted for by environment if height is 90 heritable it is 10 environmental 16 Know the difference between shared and non shared environments and know which type of environments has a larger influence on personality a Shared environment siblings share i Has larger influence on personality b Nonshared environment siblings do not share 17 Be able to define and recognize examples of an environment genetic interaction a People with different genes show different behaviors in the same environments i Effect of noise on performance 18 Be able to describe and recognize examples of the three types of genotype environment correlations i Passive a People with different genes are exposed to different environments 1 Parents provide both genes and environment yet children do nothing to obtain that environment ii Reactive evocative iii Active 1 Parents responses differ depending on child genotype 19 Be able to recognize positive and negative genotype environment correlations 1 People with particular genotypes seek out particular environments i Environment facilities the genetically influenced behavior i Environment impedes the genetically influenced behavior 20 Be able to define molecular genetics and understand how D4DR is thought to influence a Positive b Negative risk taking a Molecular genetics i Goal identify specific genes associated with personality traits b D4DR Gene i Long repeat version of D4DR novelty seeking 1 Hypothesized relationship people with long D4DR genes are
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