PPE 3003 1st Edition Lecture 8 Outline of Current Lecture I Controversy About Genes and Personality II Genes and Personality III The Human Genome IV Goals of Behavioral Genetics V Heritability VI Behavioral Genetics Methods VII Behavioral Genetics Major Findings VIII Attitudes and Preferences IX Shared versus Nonshared Environmental Influences X Genes and the Environment Two Issues XI Science Politics and Values Current Lecture A Controversy About Genes and Personality a Behavioral genetics i To what degree are individual differences due to genetic and environmental factors b Controversial i Ideological concerns 1 Equality fairness ii Eugenics B Genes and Personality a Genotype i An organism s genetic information b Phenotype i An organism s observable characteristics c Genotype affects phenotype C D E F d Phenotype is affected by environment too The Human Genome a Much of the human genome is the same for all humans b Very small number of genes differ across people c Some indirectly code for physical personality traits i Indirectly 1 Expression depends on the environment Goals of Behavioral Genetics a Determine i What percent of trait differences is due to genetics and what percent is due to environment ii How do genes and environment interact iii What environmental effects are important iv Parents teachers peers ects Heritability a Heritability i How much an individual difference is explained by genetics b Environmentality i How much of an individual difference is due to environment ii Opposite of heritability c Misconceptions i Cannot be applied to single people 1 A single individual s height for example is not 90 due to his her genes 2 It is more accurate to say that the variation between people in height is 90 due to genetic differences ii Is not constant iii Is not unchangeable iv Is not a precise statistic Behavioral Genetics Methods a Selective breeding i Obviously not with humans ii Can t be done ethically with humans 1 Dogs a Hunting dogs more aggressive dogs different purposes b Labrador gentle and trainable c Poodle allergy friendly d Labradoodle low maintenance coat friendly sociable and smart b Family studies i Correlates genetic similarity with personality similarity ii If trait is very heritable more genetic relatedness 1 More similarity on traits 2 Ex if dad and son are both high sensation seekers and second cousin is not could be genetics iii Problem 1 Families typically share genes and environment iv Family studies are never definitive c Twin studies i Monozygotic vs dizygotic twins 1 Monozygotic a Share a single fertilized egg single zygote b Share 100 of their genes 2 Dizygotic a Come form two separately fertilized eggs two zygotes ii Estimate heritability 1 Are identical MZ twins share 100 of their genes more similar than fraternal DZ twins share 50 of genes 2 If MZ twins are more similar than DZ twins a Due to heritability iii Equal environments assumption d Adoption studies i Positive correlations on traits between adopted children and adoptive parents 1 Environmental influence ii Positive correlations between adopted children and genetic parents 1 Genetic influence iii Studies get around equal environments assumption iv Representativeness 1 Are adopted children and adoptive genetic parents representative of the general population v Selective placement 1 Does a child s adoptive parents tend to be similar to his or her genetic parents G Behavioral Genetics Major Findings a The Big Five i Extraversion 1 40 60 heritable ii Neuroticism 1 30 54 heritable b Sexual Orientation i Controversial and developing area ii Genes are a modest and indirect influence on adult sexual orientation 1 20 67 heritability H Attitudes and Preferences a A lot of variance in heritability b Show some high heritability i Traditionalism for example 1 34 63 c Others show low no heritability i Belief in g d for example d Researchers don t agree on exactly what makes an attitude heritable or not e Drinking i Thought to be related to 1 Sensation seeking 2 Extraversion 3 Neuroticism ii Drinking 36 56 heritability iii Alcoholism 50 71 heritability I Shared Versus Nonshared Environmental Influences a Studies that show moderate heritability also hint at importance of environmental influences b Personality characteristics i Heritability of 30 50 with environmentality 50 70 c Example Siblings i Shared number of books in the home ii Non shared friends and teachers J Genes and the Environment Two Issues a Genotype Environment Interaction i People with different genes show different behaviors in same environment b Genotype Environment Correlation i People with different genes are exposed to different environments ii Three types 1 Passive a Parents provide both genes and environment yet children do nothing to obtain that environment b Parents verbal ability combined number of books in the house and genes leads to the child s verbal ability 2 Reactive a Parents responses differ depending on child genotype b Genes lead to how the baby responds positively to being held leads to the baby being held more 3 Active a People with particular genotypes seek out particular environments b Genes and sensation seeking lead to skydiving and drug use iii Can be negative or positive 1 Positive a Environment facilities the genetically determined behavior 2 Negative a Environment impedes the genetically determined behavior 3 Gambling example a Positive you re parents take you to casino to celebrate 21st birthday b Negative your parents have a negative view and hate gambling K Science Politics and Values a Heritable personality traits violate blank slate view b Concern about misuse of behavioral genetics findings
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