Genetics and Behavior: Nature vs. Nurture

1. Myers’ PSYCHOLOGY For AP Unit 3C The Nature and Nurture Of Behavior

2. Food For Thought How much of your behavior would you attribute to biology? How much to environment? Why?

3. Dessert for Thought How would you feel if you knew that your genes had the greatest influence on your behavior? Why?

4. 3 BIG Questions • How does genetic inheritance (our nature) and experience (nurture) influence our development? • Continuity versus stages of development? • Stability versus Change…do our personalities change as we age?

5. Nature/Nurture Quiz 1. Even complex human traits are determined by a single gene 2. People’s divorce risks are about 50% attributable to genetic factors 3. Adoptees’ traits bear more similar to their adoptive parents than to their biological parents 4. Two different children in the same family are on average as different from one another as are pairs of children selected from the general population

6. Quiz Continued 5. If after a worldwide catastrophe only Icelanders and Kenyans survived, the human species would soon be just as mixed and diverse as it is now 6. A child who hears English spoken with one accent at home and another in the neighborhood or at school adopts the accent of their peers, not their parents 7. Compared with Westerners, people in Japan exhibit greater concern for social harmony and loyalty

7. Continued 8. Seven weeks after conception, males and females remain anatomically identical 9. Even when families discourage gender typing, children still organize themselves into “boy worlds” and “girl worlds”

8. Check Your Answers! 1. False 2. True 3. False 4. True 5. False 6. True 7. True 8. True 9. True

9. Genes: Our Biological Blueprint • Chromosomes • threadlike structures made of DNA that contain the genes • DNA (deoxyribonucleic acid) • complex molecule containing the genetic information that makes up the chromosomes • has two strands-forming a “double helix”--held together by bonds between pairs of nucleotides

10. TestYour Knowledge If chromosomes are books of heredity – the words are _______________ and the letters are ___________________. Sperm is to cell as DNA is to _____________.

11. Genes: Our Biological Blueprint • Genes • biochemical units of heredity that make up the chromosomes • a segment of DNA capable of synthesizing a protein • Genome • the complete instructions for making an organism • consisting of all the genetic material in its chromosomes • Molecular geneticists are most interested in studying nucleotide sequences…human genetic diversity consists of differences in our nuclotides.

12. Molecular Genetics: Promises and Perils Molecular geneticists are trying to identify genes that put people at risk for disorders. With this kind of knowledge, parents can decide to abort pregnancies in which the fetus is suspected of having such disorders. However, this opens up a real concern regarding ethical issues involving such choices.

13. Nucleus Chromosome Gene Cell DNA Genes: Their Location and Composition

14. Evolutionary Psychology • Natural Selection • the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations • Mutations • random errors in gene replication that lead to a change in the sequence of nucleotides • the source of all genetic diversity

15. Evolutionary Psychology • Evolutionary Psychology • the study of the evolution of behavior and the mind, using the principles of natural selection • Gender • in psychology, the characteristics, whether biologically or socially influenced, by which people define male and female

16. Evolutionary Psychology Con’t • EP is not about how one species evolves into another species over time BUT is about how genetics and environment interact leading to in genetics to fit the environment. • Traits leading to survival are likely to be assed along. • Predisposed to love our children, fear animals, select healthy mates etc.

17. Criticisms of EP • Evolution does not imply genetic determinism. • Behavior can be changed. • Does not assume that organisms can compute complex math problems/formulas. • Current adaptive mechanisms in humans are not optimally designed.

18. Evolutionary Psychology • Men preferred attractive physical features suggesting youth and health • Women preferred resources and social status

19. Behavior Genetics • Behavior Genetics • study of the relative power and limits of genetic and environmental influences on behavior • Environment • every nongenetic influence, from prenatal nutrition to the people and things around us

20. Identical twins Fraternal twins Same sex only Same or opposite sex Behavior Genetics • Identical Twins (Monozygotic) • develop from a single fertilized egg that splits in two, creating two genetically identical organisms • Fraternal Twins (Dizygotic) • develop from separate eggs • genetically no closer than brothers and sisters, but they share the fetal environment

21. Twins and Procedures Behavior geneticists’ effects of shared and unique environments on total or partial genetic makeup.

22. Twins • Fraternal twins are on the rise… • Fertility drugs like Clomid • Women are waiting longer to have children • Identical twins share the 100% the same genes but can have different phenotypes… • Phenotype is how a gene expresses itself. • ie…mirror twins – differences in heritability Personality & Interests. • Sweden has the largest twin registry.

23. Behavior Genetics • Temperament • a person’s characteristic emotional reactivity and intensity • Heritability • the proportion of variation among individuals that we can attribute to genes • may vary, depending on the range of populations and environments studied

24. Heritability Continued • “Herit” part of inherit – possess something that someone has given to you. • Ability – suffix meaning “capable” – genetically passed on – it is capable of showing up in children of those who possess that quality • ie. parent to child

25. Behavior Genetics • Interaction • the dependence of the effect of one factor (such as environment) on another factor (such as heredity) • Example – people who are judged s attractive physically are more likely to get a job or promotion over someone who is less attractive. • Molecular Genetics • the subfield of biology that studies the molecular structure and function of genes

26. Environmental Influence • Two placental arrangements in identical twins

27. Rat brain cell Impoverished environment Rat brain cell Enriched environment Environmental Influence • Experience affects brain development

28. Environmental Influence • A trained brain

29. Environmental Influence • Culture • the enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next • Peer influence – slang, food and fashion preferences • Parental influence - are most influential when it comes to values, political beliefs and manners. • Norm • an understood rule for accepted and expected behavior

30. Environmental Influence • Personal Space • the buffer zone we like to maintain around our bodies • Memes • self-replicating ideas, fashions, and innovations passed from person to person

31. The Nature and Nurture of Gender • X Chromosome • the sex chromosome found in both men and women • females have two; males have one • an X chromosome from each parent produces a female child • Y Chromosome • the sex chromosome found only in men • when paired with an X chromosome from the mother, it produces a male child

32. Sex Linked Traits • Sex linked traits are passed to child fro mother through X chromosome. • Usually recessive so when father passes along another X (female), his chromosome dominates the recessive gene. • Most sex linked traits are exhibited in males because there’s only one X • ie. colourblindeness

33. The Nature and Nurture of Gender • Testosterone • the most important of the male sex hormones • both males and females have it • additional testosterone in males stimulates • growth of male sex organs in the fetus • development of male sex characteristics during puberty • Role • a set of expectations (norms) about a social position • defining how those in the position ought to behave

34. The Nature and Nurture of Gender • Gender Role • a set of expected behaviors for males and females • Gender Identity • one’s sense of being male or female • Gender-typing • the acquisition of a traditional masculine or feminine role

35. The Nature and Nurture of Gender • Gender and Culture

36. The Nature and Nurture of Gender

37. Gender Roles: Theories • Gender Schema Theory suggests that we learn a cultural “recipe” of how to be a male or a female, which influences our gender- based perceptions and behaviors. • Social Learning Theory proposes that we learn gender behavior like any other behavior—reinforcement, punishment, and observation.

38. The Nature and Nurture of Gender • Social Learning Theory • theory that we learn social behavior by observing and imitating and by being rewarded or punished • Gender Schema Theory • theory that children learn from their cultures a concept of what it means to be male and female and that they adjust their behavior accordingly

39. Reflections on Nature and Nurture