Chapter 9 The Inheritance of Personality Behavioral Genetics and Evolutionary Theory 1 Objectives Discuss two biologically based approaches to how personality might be inherited genetics evolution Discuss how these approaches can be combined with each other and with other approaches 2013 W W Norton Company Inc 2 Behavioral Genetics Attempts to explain how personality traits are passed from parent to child and shared by biological relatives Examines how genes influence broad patterns of behavior Controversy from associations with eugenics and cloning Modern research is not concerned with these issues 2013 W W Norton Company Inc 3 Behavioral Genetics Calculating Heritabilities To examine how phenotypes may be attributed to variation in genotypes Phenotype observable traits Genotype underlying genetic traits Compare similarity in personality between people who are and are not related and people who are related to different degrees Monozygotic MZ vs dizygotic DZ twins Assumption traits and behaviors influenced by genes should be more similar among more closely related people 2013 W W Norton Company Inc 4 GENES AND PERSONALITY Heritability Coefficient h2 proportion of observed variance in scores that can be attributed to genetic factors Based on the difference between the MZ and DZ correlations If MZ twins are no more similar to one another than are DZ twins then the h 2 is zero If MZ twins differ greatly from DZ twins h 2 is large Refers to variation in the population examined in a given study 2013 W W Norton Company Inc 2013 W W Norton Company Inc Behavior Genetics What Heritabilities Tell You 1 Genes matter 2 Etiology of disorders Disorders with very low heritabilities are likely to be due to environmental factors Severe vs moderate retardation 3 Insight into the effects of the environment on personality development Shared family environment does not seem to matter 2013 W W Norton Company Inc 7 Behavior Genetics What Heritabilities Tell You Does the family matter Yes No or very little Why Genetic Studies on the effect of shared family environment Research with self reports Extreme conclusion Developmental psychology Effects of parent training Delinquency love aggression psychopathology Based on behavioral observation 2013 W W Norton Company Inc 8 Think About It If you have siblings was the family environment in which you grew up the same as or different from theirs If different do these variations account for differences in how you and your sibling turned out 2013 W W Norton Company Inc 9 Behavior Genetics How Genes Affect Personality Gene environment interactions There must be an environment in order for there to be behavior Genes are not causal only provide design Environments can affect heritability Example height Heritability is lower when children have bad nutrition Environment can determine how or whether gene is expressed 2013 W W Norton Company Inc 10 Behavior Genetics The Future Researchers are working to find out which genes are associated with personality Most likely there is not one to one association Obesity gene More likely that a trait is associated with many genes each having a small effect depending on other genes and the environment 2013 W W Norton Company Inc 11 Evolutionary Personality Psychology Attempts to explain how patterns of behavior that characterize all humans originated in the survival value of these characteristics Identify common behavior patterns and then determine how the behavior was adaptive 2013 W W Norton Company Inc 12 Evolutionary Personality Psychology Evolution and Behavior Aggression and altruism increase protection Self esteem evolved to monitor how accepted we are by others Sociometer theory there is a reason why we have self esteem it lets us monitor how accepted or unaccepted we are by society in general Depression pain signals that something is wrong and must be fixed Crying may be a way of seeking social support Fatigue and pessimism may prevent wasting resources 2013 W W Norton Company Inc 13 Evolutionary Personality Psychology Evolution and Behavior Mate selection Buss 1989 37 samples representing over 10 000 individuals from 33 countries located on 6 continents and 5 islands 1 2 In all 37 samples males valued physical attractiveness and relative youth than did females signals youth and physical health and ability to have children In 36 samples females valued financial capacity relatively more than males need to provide economic resources and appropriate attitudes to support a family Both want the highest likelihood of healthy offspring who will survive and reproduce the difference is how this goal is reached 2013 W W Norton Company Inc 14 Evolutionary Personality Psychology Evolution and Behavior Mate selection some complications Women who are too thin cannot bear children Larger women used to be considered ideal Attraction is influenced by more than physical characteristics Male physical attractiveness is more important to women than it should be 2013 W W Norton Company Inc 15 Evolutionary Personality Psychology Evolution and Behavior Mating strategies Differences between men and women desired number of sexual partners faithfulness to partner selectivity of partners Will you Go out with me tonight Go to bed with me tonight Women 50 Men 50 Women 0 Men 70 2013 W W Norton Company Inc 16 Evolutionary Personality Psychology Evolution and Behavior Mating strategies Sociosexuality willingness to have sex without being in a relationship Jealousy sexual vs emotional Men report they would be more upset at sexual infidelity and women would be more jealous of emotional infidelity Explained by differences in factors that affect reproductive success 2013 W W Norton Company Inc 17 Evolutionary Personality Psychology Stress Tests 1 Methodology Backward speculation is difficult to test empirically Responses alternative explanations are always possible specific predication can be tested 2 Reproductive instinct Responses people do not have to consciously try to do what is evolutionary adaptive 3 Conservatism Responses this is scientifically irrelevant just because something is natural does not mean it is good 2013 W W Norton Company Inc 18 Evolutionary Personality Psychology Objections and Responses 4 Human flexibility Response we are evolved to behave flexibly and we can overcome innate urges 5 Gender differences are the result of social structure Really a nature vs nuture debate 2013 W W Norton Company Inc 19 Changes in Educational and Income