Slide 1ObjectivesBehavioral Genetics: Calculating HeritabilitySlide 4Behavioral Genetics: Calculating the Heritability coefficientSlide 6Slide 7Slide 8Behavior Genetics: What Heritability Can’t Tell You3 Key Facts: Genes & Personality Variation3 Key Facts: Genes & Personality Variation3 Key Facts: Genes & Personality Variation“Shared”/Nonshared Environmental Effects:Slide 14Slide 15Behavior Genetics: Molecular Genetics(Re)Thinking about Gene X Environment Interactions:Genes Sensitivity to EnvironmentGXE as “Sensitivity”GXE as “Sensitivity”Example of observed “Environment”Example of a Manipulated “Environment”Example of “Environment”Experimental GXE effect (Manipulated E, measured G)Behavior Genetics: The future…Intro to Evolutionary Personality PsychologySlide 27“Adaptation”Mutations & lactose digestion…© 2013 W. W. Norton & Company, Inc.The Personality PuzzleSixth Editionby David C. Funder Psychology of PersonalityLecture 15: 3/13/16Inheritance of Personality Stephanie Federspiel, Ph.D.1Objectives•Present an overview of two biologically based approaches to how personality might be inherited.•We will finish the behavioral genetics approach from last time and also begin presenting an evolutionary psychology perspective.Behavioral Genetics: Calculating Heritability•Behavior genetics approaches have demonstrated that the causes of MANY differences among people include BOTH genetic and environmental bases.•Heritability statistics attribute some degree of variation in phenotypes to variation in genotypes and some to variation in environmental exposures.4REMEMBER: Population level of analysis, not individual.Behavioral Genetics:What proportion of variation in a trait is due to genetic variation?Identical (MZ) Identical (MZ) Fraternal (DZ) Fraternal (DZ) Score of First Twin Score of Second Twin Score of First Twin Score of Second TwinPair 1 54 53 52 49Pair 2 41 40 41 53Pair 3 49 51 49 52 . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . r- .60 r - .40Behavioral Genetics: Calculating the Heritability coefficient4Heritability: Proportion of variance due togenetic differences (rough estimate)Height: rmz = .95 rdz = .50Due to Genetic variation: h2 = 2(rmz – rdz)2(.95 – .50) = .90, 90%Due to Environment variation = 1 - h2 1 - .90 = .10, 10%.REMEMBER: Other populations might show less heritability. Environmental variance is restricted in most populations used in Behavior Genetic Studies!7Affluent(higherheritabilityI.Q., height…)Personality?? Impoverished(lower heritabilityI.Q., height)Personality??Personality Big Five Extraversion .54Agreeableness (aggression) .42Conscientiousness .49Neuroticism .48Openness .57Big Three Positive emotionality .50Negative emotionality .44Constraint .52Psychiatric illnesses Schizophrenia .80Major depression .37Panic disorder .30-.40Generalized anxiety disorder .30Phobias .20-.40Alcoholism .50-.60Antisocial behavior (adults) .41Social attitudes Conservatism (age 20 and older) .45-.65Right-wing authoritarianism (adults) .50-.64Religiousness (adults) .30-.45Behavior Genetics: What Heritability Can’t Tell You•Nature versus nurture –You can’t use heritability to determine what percent of a trait is determined by genetics and by the environment.–Traits with little variation will have heritabilities close to zero•HOW genes affect personality –We don’t know which genes are implicated.–Genes may not even be related to brain!–Create propensities to behave in certain ways3 Key Facts: Genes & Personality Variation1) Approximately 40%* of variation in Big 5 is attributed to genetic variation. 2) Effect of NONSHARED (unique) environment appears much > effect of SHARED (common) environment (but difference seems to have been exaggerated).3) Genes (G) and environments (E) are correlated (rGE)!--This can make it hard to disentangle effects--Can make it hard to see G X E interaction (different E’s, different effects of G!)3 Key Facts: Genes & Personality Variation1) Approximately 40%* of variation in Big 5 is attributed to genetic variation (twin study). *depends on trait (E, N, O > C, A)* We don’t know which genes matter… * Specific configurations seem important (nonadditive): b/c Adoption studies = LOWER estimates (20 – 30%), b/c MZ more than 2x as similar as DZ! EFFECTS of genes are INTERACTIVE and multiplicative123 Key Facts: Genes & Personality Variation2) For a long time, researchers reported that effects of “ Nonshared” E was much > Shared E *MZ twins raised apart generally as similar as MZ together!!!2 major limitations:Limited types of dataLimited review of traits.“Shared”/Nonshared Environmental Effects:SHARED (suggested 5%?)Family income/Social classParent EducationPresence of Father/MotherNeighborhoodSchoolFamily conflict“General” parental techniques?(Might not really be shared!)NONSHARED (suggested 35%?)Perinatal traumaAccidental eventsConstellation/“Place” in familySibling mutual interactionUnequal parental treatmentInfluences outside family:---teachers, friends, activitiesPERCEPTIONS of environment!3) Genes are expressed in environments, and are even associated with the experience of particular environments (rGE, correlation)!Active (niche-picking)Evocative effectsPassive effects (parents offer genese + environment)•The same Genes may have different effects on outcomes given different environments (and/or different combinations of other genes!)3 Key Facts: Genes &Personality VariationBehavior Genetics: Molecular Genetics•Methods of molecular biology allow new Q’s:–Do traits correlate with specific genetic diffs? (NOTE: Probably many genes involved in complex traits!)(1) MAOA (affects many NT levels)•Control of aggression; perception of hostility/social threat(2) DRD4 (dopamine receptors & novelty seeking)•Risk for aggression/externalizing, attention problems(3) 5-HTT (serotonin transporter & anxiety)•Allele frequency varies geographically.–Are there specific gene X environment interactions?•Some variants might only by risky in certain environments!•Maybe they could even be an asset in other environments?(Re)Thinking about Gene X Environment Interactions:•Initially G X E interactions were identified and framed as increased vulnerability to stressors:•Childhood abuse + Low Activity MAOA gene  antisocial behavior•Life stress + lower activity 5-HTT gene  depression?•Insensitive mother + DRD4