Exam 3 Learning Objectives Genetics Heritability Lecture 8 1 Be able to define genome Genome all of our genes 2 Understand the hierarchy in the genome e g chromosomes are made up of what Genes are made up of what Genome Chromosomes 46 arranged in pairs Genes basic unit of inheritance DNA 3 Be able to define behavioral genetics Behavioral genetics to what degree are individual differences due to genetic environmental factors 4 What are the controversies surrounding behavioral genetics Controversies Genetic determinism Eugenics the idea of improving genetic quality Genes environment interact Example Antisocial personality genetic influence gives person the right to behave a certain way 5 What are the three major questions asked by behavioral geneticists 1 What causes variability in a trait genes vs environment 2 What environment effects are important Parents teachers peers 3 How do genes and environment interact Parents don t actually have impact on how their children turn out Being a really bad parent can have an impact on the child s outcome 6 What is heritability Heritability how much an individual difference is explained by genetics 7 Be familiar with the misconceptions about heritability and be able to recognize examples Heritability CANNOT be applied to single people A single individual s height is not 10 due to their environment It is more accurate to say that the variation between people in height is 10 due to the environment Example in class Height has 90 heritability in the population how much of your specific height is due to specific genes or to the environment Extraversion is 60 heritable does that mean 60 of your extraversion is heritable No we look at the entire class Heritability is NOT constant unchangeable Heritability only applies to a population at one point in time Example in class obesity is somewhat heritable your genes may cause you to gain The more similar the environment between people the higher heritability will be wait But there are environmental factors that influence weight o Everyone has the same diet same exercise same check up at the doctor obesity would go up controlling the environment Example 2 measure heritability in height in a different country where some people had no access to food and some people had access to food o Heritability of height go down because the environment is different o The greater the difference in the environment the greater the chance that the heritability would decrease Heritability is NOT a precise statistic Only as good as the sample used Homogenous group of people overestimate heritability of the trait Affected by measurement error 8 Be able to list and define the four methods used in behavioral genetics Can t be done ethically with humans 1 Selective breeding Only works if a desired trait is heritable 2 Family studies 3 Twin studies Monozygotic twins If selective breeding for a trait is successful the trait is at least somewhat genetic Correlates genetic similarity with personality similarity If trait is heritable more genetic relatedness more similarity on traits Problem families share genes and environment family studies are never definite Share a single fertilized egg a single zygote monozygotic Share 100 of their genes Dizygotic twins Come from two separately fertilized eggs two zygotes dizygotic Share about 50 of their genes Monozygotic vs Dizygotic twins Estimate heritability o Are identical monozygotic MZ twins more similar than fraternal o If MZ twins are more similar than DZ twins on a given trait due to dizygotic DZ twins heritability Do twin studies eliminate problem from family studies Equal environments assumption Environment experienced by identical twins no more similar than environments shared by fraternal twins 4 Adoption studies Correlations on traits between adopted children and adoptive parents environmental influence Correlation between adopted children and genetic parents genetic influence Potential problem Ideal study Twins reared apart Representativeness Selective placement of adopted children Combines strengths of twin and adoption studies 9 Know advantages and disadvantages associated with each method from behavioral o If successful you know that the trait is at least somewhat genetic genetics Selective Breeding Advantages Disadvantages o Not Ethical Family Studies Advantages Disadvantages Twin Studies Disadvantages o Correlates genetic similarity with personality similarity o Families share genes and environment o Never definitive absolute o Families share genes and environment o Equal environments assumption The wrong assumption that environments shared by identical twins are no more similar than environments shared by fraternal twins 10 Know the difference between monozygotic and dizygotic twins Monozygotic twins Share a single fertilized egg a single zygote monozygotic Share 100 of their genes Dizygotic twins Come from two separately fertilized eggs two zygotes dizygotic Share about 50 of their genes 11 Be able to compute heritability if I give you the correlations for monozygotic and dizygotic twins Heritability Quotients Neuroticism DZ twins correlated at 18 MZ twins correlated at 41 Heritability 2x differences in correlation Heritability 2 41 18 Heritability 2 23 46 Heritability 46 12 Which kind of study generally gets higher heritability scores Adoption or twin studies Twin vs Adoption studies MZ twins are MUCH more similar to each other than DZ twins But adopted children aren t tremendously more similar to their biological siblings than their adopted siblings There might be something special about having ALL your genes in common with someone 13 What is nonadditive genetic variance The interaction of genes effects similarity between MZ and DZ twins and siblings Since MZ twins share 100 of their genes they are tremendously more similar than DZ or regular sibling because their genes react with each other the same way while DZ and regular siblings only have 50 of the same genes 14 Be familiar with the heritability of the extraversion neuroticism drinking and alcoholism Extraversion 40 60 heritable Neuroticism 30 54 heritable Drinking related to Sensation seeking Extraversion Neuroticism Drinking 36 56 Alcoholism 50 71 15 Know that any variance not accounted for by genetics is accounted for by environment if height is 90 heritable it is 10 environmental As said in class percentage quotient height 90 due to genetics 10 due to environment 16 Know the difference between shared and non
View Full Document
Unlocking...