Psych of Personality Test 2 Chapter 6 Learning Objective p 138 182 1 Be able to define genome and understand the hierarchy in the genome e g Chromosomes are made up of what Genes are made up of what a Genome all of our genes b Chromosomes 23 pairs one set from each parent c DNA made up of nucleotides different proteins d Genes chromosomes genes DNA e i Human vs ape 96 2 Be able to define behavioral genetics The human genome very small number of genes are different across people a Behavioral genetics to what degree are individual differences due to genetic environmental factors b We know that both are a factor c Known to be genetic mostly physical height skin color eye color some diseases Huntington s 3 What are the three major questions asked by behavioral geneticists a What causes variability in a trait genes vs environment heritability estimates b Which environmental effects are important e g parents teachers peers parents teachers peers 4 What is heritability c How do genes and environment interact most likely combination of both a Heritability how much an individual difference is explained by genetics b Ex height is probably genetic but nutrients you receive matters too heritability for height is 90 and 10 comes from environment 5 Be familiar with the misconceptions about heritability and be able to recognize examples a Cannot be applied to a single people i A single individual s height for example is not 10 due to their environment ii It is more accurate to say that the variation between people in height is 10 due to the environment iii Only done on entire group of people b Is not constant unchangeable In 20 years height might be 60 heritability i Heritability only applies to a population at one point in time ii iii The more similar the environment between people the higher the heritability will be iv More similar environment gets then heritability has a higher influence v If environment gets more diverse then less differences due to genetics vi Huge famine heritability of height will go down c Is not a precise statistic i Only as good as the sample used ii Just a correlation 6 Be able to list and define the four methods used in behavioral genetics including the advantages and disadvantages of each method a Selective breeding to breed b Family studies i Can t be done ethically with humans ii Only works if desired trait is heritable iii Advantages works if trait is heritable the more heritable a trait is the easier it will be iv Disadvantages cannot ethically do this with humans c Twin studies If trait is heritable more genetic relatedness more similarities on traits i Correlates genetic similarity w personality similarity ii iii Problem families share genes and environments iv Family studies are never definitive v Advantages if trait is heritable more genetic relatedness more similarity on traits provide heritability estimates vi Disadvantages people who share more genes probably share similar environment family studies are never definitive violate equal environments assumption i Advantages environment is most likely constant but how much genetics is varied you can test better what is more influential provide both heritability and environmental estimates ii Disadvantages sometimes violate equal environments assumption iii Monozygotic twins 1 2 Share a single fertilized egg a single zygote monozygotic Share 100 of their genes iv Dizygotic twins 1 Come from two separately fertilized eggs two zygotes dizygotic 2 Share about 50 of their genes v vi Monozygotic vs Dizygotic twins 1 Estimate heritability a Are identical monozygotic MZ twins more similar than fraternal dizygotic DZ twins b If MZ twins are more similar than DZ twins on a given trait due to heritability vii Computing heritability quotients 1 Neuroticism a DZ twins correlated at 18 b MZ twins correlated at 41 c Heritability 2x difference in correlation d Heritability 2 41 18 e Heritability 2 23 46 f Heritability 46 viii Do twin studies eliminate problem from family studies ix Equal environments assumptions 1 Environment experienced by identical twins no more similar than environments shared by fraternal twins d Adoption studies i Advantages provide both heritability and environmentally estimates get around problem of equal environments assumption ii Disadvantages adopted kids might not be representative of population problem of iii Correlations on traits between adopted children and adoptive parents environmental selective placement influence iv Correlations between adopted children and genetic parents genetic influence v Potential problem 1 Representativeness 2 Selective placement of adopted children Ideal study vi vii Twin reared apart e Twin vs adoption studies 1 Combines strengths of twin and adoption studies i MZ twins are MUCH more similar to each other than DZ twins ii But adopted children aren t tremendously more similar to their biological siblings than iii There might be something special about having ALL your genes in common with their adopted siblings someone iv Nonadditive genetic variance 7 Know the difference between monozygotic and dizygotic twins a Look at question above 8 Be familiar with the heritability of the following traits extraversion neuroticism and the rest of the Big 5 temperament aggressiveness violent crime traditionalism drinking and alcoholism a The Big Five i Extraversion 40 60 heritability 1 Adoption lower heritability ii Neuroticism 30 54 heritability iii All the Big Five 50 heritability 1 2 Pretty stable over time fact it is built within you will remain pretty stable Things with large genetic influence will remain more stable iv Activity level temperament 50 heritability v Aggressiveness 51 72 heritability vi Psychopathic traits moderately heritable vii Violent crimes 50 heritable viii Traditionalism 59 heritable ix Drinking 36 56 1 Drinking related to Sensation seeking a b Extraversion c Neuroticism x Alcoholism 50 71 xi Propensity to marry 68 9 1 Divorce neuroticism husband s impulsivity probably moderately heritable Know that any variance not accounted for by genetics is accounted for by environment if height is 90 heritable it is 10 environmental a Studies that show moderate heritability also hint at importance of environmental influences 10 Know the difference between shared and non shared environments and know which type of environments has a larger influence on personality Shared environment siblings share a b Nonshared environment siblings do not share i Accounts for more
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