PPE 3003 1st Edition Lecture 8 Outline of Current Lecture I. Controversy About Genes and PersonalityII. Genes and PersonalityIII. The Human Genome IV. Goals of Behavioral GeneticsV. 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 LectureA. Controversy About Genes and Personalitya. Behavioral geneticsi. To what degree are individual differences due to genetic and environmental factorsb. Controversiali. Ideological concerns1. Equality/fairnessii. Eugenics B. Genes and Personalitya. Genotypei. An organism’s genetic informationb. Phenotypei. An organism’s observable characteristics c. Genotype affects phenotyped. Phenotype is affected by environment too C. The Human Genomea. Much of the human genome is the same for all humans b. Very small number of genes differ across peoplec. Some indirectly code for physical/personality traitsi. Indirectly1. Expression depends on the environmentD. Goals of Behavioral Geneticsa. Determinei. What percent of trait differences is due to genetics and what percent is due to environmentii. How do genes and environment interactiii. What environmental effects are importantiv. Parents, teachers, peers, ectsE. Heritabilitya. Heritabilityi. How much an individual difference is explained by geneticsb. Environmentality i. How much of an individual difference is due to environment ii. Opposite of heritability c. Misconceptionsi. Cannot be applied to single people1. A single individual’s height, for example, is not 90% due to his/her genes2. It is more accurate to say that the variation between people in height is 90% due to genetic differences ii. Is not constantiii. Is not unchangeable iv. Is not a precise statisticF. Behavioral Genetics Methodsa. Selective breeding i. Obviously not with humansii. Can’t be done ethically with humans1. Dogsa. Hunting dogs, more aggressive dogs, different purposes b. Labrador: gentle and trainablec. Poodle: allergy friendlyd. Labradoodle: low maintenance coat, friendly, sociable, andsmart b. Family studiesi. Correlates genetic similarity with personality similarity ii. If trait is very heritable, more genetic relatedness 1. More similarity on traits2. 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 studiesi. Monozygotic vs. dizygotic twins1. Monozygotic a. Share a single fertilized egg (single zygote) b. Share 100% of their genes2. Dizygotic a. Come form two separately fertilized eggs (two zygotes)ii. Estimate heritability1. 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 assumptiond. Adoption studiesi. Positive correlations on traits between adopted children and adoptive parents1. Environmental influenceii. Positive correlations between adopted children and genetic parents 1. Genetic influence iii. Studies get around equal environments assumption iv. Representativeness1. Are adopted children and adoptive/genetic parents representativeof the general populationv. Selective placement1. Does a child’s adoptive parents tend to be similar to his or her genetic parents G. Behavioral Genetics Major Findings a. The Big Fivei. Extraversion1. 40-60% heritable ii. Neuroticism1. 30-54% heritableb. Sexual Orientationi. Controversial and developing areaii. Genes are a modest and indirect influence on adult sexual orientation1. 20-67% heritability H. Attitudes and Preferencesa. A lot of variance in heritability b. Show some high heritabilityi. Traditionalism, for example 1. .34-.63c. Others show low/no heritabilityi. Belief in g-d, for exampled. Researchers don’t agree on exactly what makes an attitude heritable or not e. Drinkingi. Thought to be related to1. Sensation-seeking 2. Extraversion3. Neuroticism ii. Drinking: 36-56% heritabilityiii. Alcoholism: 50-71% heritability I. Shared Versus Nonshared Environmental Influences a. Studies that show moderate heritability also hint at importance of environmentalinfluencesb. Personality characteristicsi. Heritability of 30-50% with environmentality= 50-70%c. Example: Siblingsi. Shared: number of books in the homeii. Non-shared: friends and teachers J. Genes and the Environment: Two Issues a. Genotype-Environment Interactioni. People with different genes show different behaviors in same environmentb. Genotype-Environment Correlationi. People with different genes are exposed to different environments ii. Three types1. Passivea. Parents provide both genes and environment, yet children do nothing to obtain that environmentb. Parents verbal ability combined number of books in the house and genes leads to the child’s verbal ability 2. Reactivea. Parents responses differ depending on child genotypeb. Genes lead to how the baby responds positively to being held leads to the baby being held more 3. Activea. People with particular genotypes seek out particular environmentsb. Genes and sensation seeking lead to skydiving and drug use iii. Can be negative or positive1. Positivea. Environment facilities the genetically determined behavior2. Negative a. Environment impedes the genetically determined behavior3. Gambling examplea. Positive: you’re parents take you to casino to celebrate 21stbirthdayb. Negative: your parents have a negative view and hate gamblingK. Science, Politics, and Valuesa. Heritable personality traits violate “blank slate” viewb. Concern about misuse of behavioral genetics
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