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Genetics, Environment, and Behavior

Genetics, Environment, and Behavior. How do they interact?. Identical twins reared apart. Elyse Schein and Paula Bernstein. Photo: Elena Siebert, 2007. Methods of behavior genetics. Twin studies Adoption studies Temperament studies

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Genetics, Environment, and Behavior

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  1. Genetics, Environment, and Behavior How do they interact?

  2. Identical twins reared apart • Elyse Schein and Paula Bernstein Photo: Elena Siebert, 2007

  3. Methods of behavior genetics • Twin studies • Adoption studies • Temperament studies • Heritability: Percentage of variability that can be connected to genes. • Molecular genetics

  4. Variation • Genotypes vary, except in identical twins • Environments vary, even for identical twins • And this may start at the twinning point. • Consequently, phenotypes vary: We are different from one another • Nonetheless, we are far more similar than we are different from one another.

  5. Genetics • Chromosome pairs and meiosis • Protein synthesis recipes • Expression of alleles • Homozygous alleles • Heterozygous alleles • Dominant alleles • Recessive alleles • Polygenic control • No genes for behavior

  6. Evolutionary psychology • An old idea is currently popular again • Emphasis is on natural selection • Or is it artificial selection? • Example of mate selection • Are all men potential rapists?

  7. Criticism of evolutionary psychology: • Backward reasoning: an effect looking for a cause • An example of post hoc reasoning. • Selective use of research results: Infidelity is overestimated. • Casual sex has far lower fertility than committed sex. • The theory plays on gender stereotypes

  8. More criticism • Other causes: socialization pressure, family life • Female sexuality is highly variable, especially across time and situations • Mate preferences are culture-related (Eagly & Wood, 1999) • Male (and female) relatives of females might protect or take revenge—and women can protect themselves, as Martha McGaughey (2008) points out in The Caveman Mystique.

  9. And a new, killer study (Farthing, 2005): • Men are more impressed by other men who take risks. • Women are not. • Women prefer altruistic men. • But, Farthing speculates, perhaps the higher status of risk-taking men among other men makes them more attractive to women.

  10. Gender influences • Sex-linked traits • Gene on sex chromosomes • Sex-influenced traits • Interaction of genetics and environment • Hormones are key variables

  11. Molecular genetics • What are the specific genes that influence behavior? • For example, what genes contribute to Bipolar Disorder? • Risk prediction and the genetic test for Huntington’s disease: Does technology make decisions easier?

  12. Molecular genetics: Genetic abnormalities • Mutations: Hemophilia • Aberrations: Cri-du-chat (5p-) syndrome • Interaction of genetics and environment • Genetic disorders • Down syndrome: Genetic but not hereditary • Huntington’s disease: Genetic and hereditary, no interaction with environment • PKU: Genetic and hereditary, interaction with environment

  13. Molecular genetics of behavior • Animal breeding: Artificial selection • Tame foxes (Trut, 1999) • Eugenics • Family studies: Concordance of bipolar disorder • Twin studies • Do you have a missing twin? • Adoption studies • An example: Schizophrenia

  14. Environmental influences • Prenatal environment • Monochorionic and dichorionic twins • Enriched vs. impoverished environments • Growth vs. pruning • The second language-learning hypothesis is now being questioned • Peer influence: Food choice, accent, smoking • Time spent • Access to peers

  15. More environmental influences • Parents • Preferences • Personality • Culture • Norms • Collective vs. individual emphasis • Gender • Aggression, social power, and social connection

  16. Sociobiology • Parental investment • The incest taboo • Altruism • Kin selection • Reciprocal altruism

  17. Ethnocentrism • Altruism in the Inuit • Kin selection • Familiarity

  18. Critical thinking about ethocentricity • How is the question framed? Does it lead us down one path of thinking? • What are our predispositions and assumptions ? What pattern of thinking would make us look good or feel better about ourselves? • Avoid fallacious thinking: The universality fallacy and the naturalistic fallacy

  19. Men prefer, in order: 1. Kindness, understanding 2. Intelligence 3. Physical attractiveness* 4. Exciting personality 5. Good health 6. Adaptability 7. Creativity 8. Desire for children 9. College graduate 10. Good heredity Women prefer, in order: 1. Kindness, understanding 2. Intelligence 3. Exciting personality 4. Good health 5. Adaptability 6. Physical attractiveness* 7. Creativity 8. Good earning capacity+ 9. College graduate 10. Desire for children What do we look for in a mate? (Buss, 1998)

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