Child Development: Chapter 4 How Children Develop Nature through Nurture

1. Child Development: Chapter 4How Children DevelopNature through Nurture

2. Chapter Outline • The Study of Genetics and Behavior • The Interaction of Genes and Environment • The Study of Culture and Behavior

3. The Study of Genetics and Behavior • How We Study Genes and Behavior • How Do Genes Work? • Genetic Disorders

4. Nature versus Nurture?Nature through Nurture! • Throughout history the idea of whether our lives are determined by our genes or by the environment has shifted from one extreme to the other. • D. O. Hebb: asking whether behavior is due to nature or to nurture is similar to asking whether the area of a rectangle is due to its length or its width (Meaney, 2004). • Genetic and environmental influences are entangled in complex ways.

5. How We Study Genes and Behavior • Molecular genetics: Identification of particular genes to discover how these genes work within the cell. • Behavioral genetics: Determining the degree of genetic basis for a behavior, a trait, or an ability through studies of twins and adopted children

6. Behavioral genomics: Research that links behaviors, traits or abilities with specific genes.

7. The Human Genome Project • The Human Genome Project mapped all the genes that make up the human body • http://www.youtube.com/watch?v=ubQsaoHBxsU&feature=fvw • 25,000-30,000 genes determine everything about our genetic inheritance. • We know what only about half of these genes actually do.

8. Results of the Human Genome Project: Chromosome 12

9. Our Genetic Beginnings • Egg and sperm unite to form a zygote. • 23 chromosomes from each pair up to form 23 pairs of chromosomes. • 22 are autosomes • The 23rd is the pair that determines the sex: XX or XY. • The father’s sperm determines the sex of the child by contributing either an X or a Y chromosome

10. Female and Male Chromosomes

11. Chromosomes, Genes, DNA, and Bases (GATC) • Chromosomes are made up of • Genes, which are made up of • DNA, which is made up of • 4 nitrogenous bases: • Guanine (G), adenine (A), thymine (T), cytosine (C) • The order of the bases determines which proteins are produced which make the body develop and perform all its activities.

12. Which combination produces a protein? • How to divide the series: ATCATCTTTGGTGTT • How would you divide the following series of letters? • Gotothegrocerystorepickupmilkcomehome

13. NOT: Got othegro cerystorepickupm ilk comeho me • BUT RATHER Go to the grocery store. Pick up milk. Come home. Scientists must find the combinations in the sequences that make sense.

14. Mendelian Inheritance: Dominant and Recessive Genes • Most genes are paired with a gene on the matching chromosome. • One of these 2 paired genes may be dominant and one recessive. • Your genotype contains all the genes in your body. • Your phenotype is which genes are expressed in your body.

15. Dominant genes will be expressed in your phenotype. • Recessive genes will only be expressed if they are paired with another recessive gene.

16. Eye color and genes

18. Recessive gene disorders • Tay-Sachs disease • Sickle-cell anemia

19. One gene: one outcome? • The field vole and the mountain vole: • One gene determines whether they mate for life or “play the field”. • Can this be true for human beings? What else would be involved besides (or in addition) to a particular gene?

20. Many genes: one outcomeOne gene: many outcomes • Polygenic inheritance: many genes interact together to produce a particular trait or behavior • Pleiotropic effects; Any single gene can have many very different effects.

21. Genetic disorders • Single gene disorders • Tay Sachs disease • PKU • Sickle cell anemia • Cystic fibrosis

22. The problem with the Y-chromosome • The Y-chromosome is small and carries few genes. • It pairs with an X-chromosome with lots of genes. • Any recessive genes on the X-chromosome that do not have a partner on the Y-chromosome will be expressed in the phenotype.

23. Therefore, boys are more prone to genetic disorders than girls. • For example • Color-blindness • Hemophilia • Duchenne muscular dsytrophy

24. Genetic disorders • Chromosomal disorders: • Down syndrome: one extra chromsome #21 • Klinefelter syndrome: XXY • Turner syndrome: XO • Fragile X syndrome: One gene segment (CGG) on the X chromosome is repeated 200 times, rather than 5–40 times.

25. Genetic counseling and testing • In each pregnancy, any couple statistically has a 3% chance of having a child with a genetically based disorder. Those at higher risk may have genetic counseling and/or testing: • Family history of genetic disorders • Blood tests for certain genes before pregnancy

26. During pregnancy: • blood tests – alpha-feta protein test • Amniocentesis • Chorionic villus sampling (CVS)

27. Interaction of Genes and Environment • How the environment shapes gene expression • How genes shape the environmental influences

28. How the environment shapes gene expression • Canalization: The degree to which the expression of a gene is influenced by the environment • Epigenetics: A system by which genes are activated or silenced in response to events or circumstances in the individual’s environment

29. Interaction of genes and the experience of child abuse

30. How genes shape the environmental influences • Passive gene-environment interaction: When a child’s family shares his own genetically determined abilities and interests. • Active gene-environment interaction: When one’s genetic endowment becomes a driving force for children to seek out experiences that fit their genetic endowments.

31. Evocative gene-environment interaction: When children’s genetic endowment causes them to act in a way that draws out or “evokes” certain responses from those around them.

32. Study of the role of genes in behavior: Behavioral genetics • Studies of adopted children • Concordance rate with biological parents and adoptive parents • Studies of identical (MZ) twins compared with non-identical (DZ) twins • Studies of identical twins reared apart http://www.youtube.com/watch?v=REhKa3_oHL8

33. The study of culture and behavior: Environment effects • Culture: behaviors, norms, beliefs, and traditions that promote the survival of a group in a particular environmental niche. • It is a way of describing similarities within one group of people and differences between groups of people.

34. Difference versus deficit • Deficit model: other cultures do not live up to one’s own standards • Difference model: other cultures must be understood in their own context

35. Cultural values: Individualism and collectivism • Individualism The cultural value that emphasizes the importance of the individual with emphasis on independence and reliance on one’s own abilities • Collectivism: The cultural value that emphasizes obligations to others within your group • http://www.youtube.com/watch?v=4uFa0hBPqOY

36. What are your cultural values? Agree or disagree: • 1. I tend to do my own thing, and others in my family do the same. • 2. To understand who I am, you must see me with members of my group. • 3. I take great pride in accomplishing what no one else can accomplish. • 4. To me, pleasure is spending time with others. • 5. It is important to me that I perform better than others on a task. • 6. I would help, within my means, if a relative were in financial difficulty. • 7. I am unique—different from others in many respects. • 8. I make an effort to avoid disagreements with my group members. • 9. I like my privacy. • 10. How I behave depends on whom I am with, where I am, or both. • 11. I know my weaknesses and strengths. • 12. I have respect for the authority figures with whom I interact. • 13. I always state my opinions very clearly. • 14. I would rather do a group paper or lab than do one alone.

37. Transmitting culture to children • American mothers promote independence in feeding: • Puerto Rican mothers promote interdependence in feeding:

38. Conclusion • Genes influence the environment • The environment influences gene expression • The interaction is complex and research is ongoing on this important topic. • BUT • We now know that we are not formed entirely by our genes and we are not formed entirely by our environment.