Personality Exam 3 Study Guide Ch 6 7 Lecture 8 Genetics Personality The human genome o Genome All of our genes complete set of DNA o Genome Chromosomes Genes DNA o A very small numbers of genes differ across people We share 96 with monkeys Behavioral Genetics o Behavioral Genetics genetic and environmental factors To what degree are individual differences due to Genes vs environment Eugenics o Controversy about genes personality Aims to improve genetic quality of human population Genetic determinism Genes and environment interact o Goals of behavioral genetics What causes variability in a trait genes vs What environmental affects are important e g How do genes and environment interact environment parents teachers peers Heritability o What is heritability genetics o Misconceptions How much an individual difference is explained by Heritability cannot be applied to single people A single individuals height for example is not 10 due to their environment It is more accurate to say that the variation between people is 10 due to their environment Heritability is not constant unchangeable Heritability only applies to a population at one The more similar the environment between point in time people the higher heritability will be Heritability is not a precise statistic Only as good as the sample used o Four methods Behavioral Genetics Methods Selective breeding Family studies Twin studies Adoption studies o Selective Breeding Can t be done ethically with humans Only works if a desired trait is heritable If selective breeding for a trait is successful the trait is at least somewhat genetic o Family Studies Correlates genetic similarity w personality similarity If trait is heritable more genetic relatedness more similarity on traits Problem Families share genes and environment Family studies are never definite o Twin Studies Dizygotic twins Monozygotic twins monozygotic Shared a single fertilized egg a single zygote Share 100 of their genes Come from two separately fertilized eggs two Share about 50 of their genes Estimate heritability zygotes dizygotic Are identical MZ twins more similar than Monozygotic vs Dizygotic twins fraternal DZ twins If MZ twins are more similar than DZ twins on a given trait due to heritability Computing heritability quotients Neuroticism DZ twins correlated at 18 MZ twins correlated at 41 Heritability 2x difference in correlation Heritability 2 41 18 Heritability 2 23 46 Heritability 46 Do twin studies eliminate problem from family Equal environments assumption studies Environment experienced by identical twins no more similar than environments shared by fraternal twins o Adoption Studies Correlations on traits between adopted children and Correlations between adopted children and genetic Potential problem adoptive parents environmental influence parents genetic influence Representativeness Selective placement of adopted children o Nonadditive Genetic Variance The configural or interactive influence of genes on Has been invoked to explain why the ratio of trait traits Interaction of genes concordance for MZ twins and DZ twins is sometimes greater than 2 0 as in the case of recent studies on extroversion o Heritability of Extroversion 40 60 Neuroticism 30 54 Drinking Alcoholism In order 36 56 50 71 Alcoholism extroversion drinking neuroticism Note Any variance not accounted for by genetics is accounted for by the environment if height is 90 heritable it is 10 environmental Note Drinking is related to extroversion sensation seeking and neuroticism o Shared vs non shared environment on personality Non shared environment appears to have more effect Effects of shared similarity Effects of non shared differences o Environment Genetic Interaction the same environments People with different genes show different behaviors in Ex Effect of noise on performance o Genotype environment correlations People with different genes are exposed to different Passive environments Parents provide both genes and environment yet children do nothing to obtain that environment genes Child s verbal ability Ex Parent s verbal ability Books in house Reactive evocative children genotype held baby is held more Parents responses differ depending upon Ex Genes Baby response positively to being Active People with particular genotypes seek out particular environments Ex Sensation seeking skydiving drugs motorcycle stunts o Positive Negative genotype environment Environment facilitates the genetically influenced Environment impedes the genetically influenced correlations Positive behavior Negative behavior o Molecular Genetics Goal D4DR Gene Identify specific genes associated with personality traits Influences risk taking novelty seeking relatively unresponsive to dopamine Long repeat version of this gene increased Hypothesis People with long D4DR genes are Ch 6 Book Objectives 1 Which three traits of the Big 5 have been shown to be the most heritable Openness extroversion and neuroticism 2 What is emergenesis An emergent property of a configuration of genes Combination of interacting genes Some personality characteristics may be a product of emergenesis whereby a unique combination of genes produces an effect that would not be produced in even an attenuate form by the parts that make up the configuration 3 What differences are found between first borns and younger siblings Older children More likely to identify strongly with parents Adopt traditional viewpoints of authority Younger borns contrarian skeptical attitude towards authority More dominant extraversion More conscientious Conservative power oriented Score higher on achievement tests Want to define themselves over and against first More likely to be rebellious and More open to innovation and change Open to experience Competitive Agreeable 4 Know the six kinds of non shared family effects Perinatal trauma Differentiates child from all other family Injuries or damage sustained by fetus before birth members from the beginning Accidental events Ex physical injuries or winning a prize Chance happenings and lucky breaks may have an impact on personality differentiating them further from other family members Family constellation Birth order Birth spacing Alliances competing cooperating adopting a Sibling mutual interaction wide range of social roles Unequal parental treatment Ex mom always liked you the most Ex Dad played sports with son but ignored daughter Influence outside the family Teachers peers etc Lecture 9 Motives Psychoanalysis o Motive
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