Expression of Genetic Effects in the Environment. Expression of Genetic Effects in the Environment

Transcription

1 Expression of Genetic Effects in the Environment Genotype/Environment Correlations: Passive G/E Cs: Children inherit genetic tendencies from their parents and parents provide environments that match their own genetic tendencies Example: Intelligent parents generally have bright children and also provide many learning opportunities for their kids Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 22 Expression of Genetic Effects in the Environment Evocative G/E Cs: Child s genetic tendencies elicit environmental stimulation that support that trait Example: Happy outgoing child elicits smiles and friendly responses from others Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 23 1

2 Expression of Genetic Effects in the Environment Active G/E Cs: Children seek out niches that reflect their genetic aptitudes Athletic kids seek out physical activities, intellectual kids spend time at the library, etc. Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 24 Expression of Genetic Effects in the Environment Genotype/Environment Interactions: The effects of heredity and environment combine in a particular way, so that individual outcomes are not precisely predictable from knowledge of one factor alone Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 25 2

3 Genotype/environment interaction for the effects of PKU depending on diet PKU (genes) No Yes Level of phenyalanine in diet (environment) Low Normal intelligence Normal intelligence Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 26 Normal Normal intelligence Mental retardation Hypothetical genotype/environment interaction for physique Genetic predisposition toward leanness Genetic predisposition toward heaviness Scanty Diet Normal Abundant Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 27 3

4 Hypothetical gene/environment interaction for intelligence High Level of Intelligence High genetic endowment for intelligence Low genetic endowment for intelligence Low Deprived Average Enriched Learning Environment Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 28 Expression of Genetic Effects in the Environment Epigenetic view: Development is the result of an ongoing, bidirectional interchange between heredity and environment Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 29 4

5 Quote The processes involved in behavioral and psychological development have certain metaphorical similarities to cooking. Both the raw ingredients and the manner in which they are combined are important. Timing also matters. In the cooking analogy, the raw ingredients represent the many genetic and environmental influences, while cooking represents the biological and psychological processes of development. Bateson, P. and Martin P. (2000). Design for a Life: How Behavior and Personality Develop. New York: Simon and Schuster. (p. 16) Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 30 II. Studying Genetic Influence on Behavior Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 31 5

6 Behavior Genetics and Types of Genetic Studies Behavior Genetics: Study of hereditary influence on behavior and traits Searching for specific genes that influence specific traits The effects of naturally occurring genetic abnormalities Study animals that have a specific gene knocked out Correlate a trait with the presence of a particular gene in the population Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 32 Behavior Genetics and Types of Genetic Studies Searching for general genetic influence: Selective Breeding: Mate together animals with a certain trait attempting to breed a strain of animals with that trait Family (Resemblance) Studies: Do traits run in human kinship lines? Inconclusive Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 33 6

7 Behavior Genetics and Types of Genetic Studies Adoption Studies: Compare the traits of adopted children to their birth parents and to their adoptive parents Who do they resemble more? Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 34 Logic of Adoption Studies Adopted Child Compared With Birth Parent (Heredity) Adoptive Parent (Environment) Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 35 7

8 Behavior Genetics and Types of Genetic Studies Twin Studies: Compare identical twins with other groups of people Are people who share more genes more similar in their traits than people who share fewer genes? Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 36 Logic Of Twin Studies Group Genes Shared Identical twins 100% Fraternal twins 50% on average Non-twin biological siblings 50% on average Offspring and parent 50% Nephew/niece and aunt/uncle 25% on average Half-siblings 25% on average Adopted and adoptive 0% on average Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 37 8

9 Heritability and Statistical Estimates Heritability: The amount of variation in a trait within a large group of people that can be accounted for by genetic differences among the group members Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 38 Heritability and Statistical Estimates Common statistical estimates: Concordance rates: percent of pairs of people in which both members have a category trait if one has it Correlation coefficient: Degree and direction of relationship between two continuous variables Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 39 9

10 Research on the Heritability of Human Traits Schizophrenia: Concordance rates for people with varying degrees of genetic relationship to patients with schizophrenia: Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 40 Concordance Rates for Schizophrenia Relationship to schizophrenic patient Concordance Identical twin 48% Offspring of two schizophrenic patients 46% Fraternal twin 17% Offspring of one schizophrenic patient 13% Non-twin biological sibling 10% Nephew or niece 3% Unrelated person in general population 1% Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 41 10

11 Research on the Heritability of Human Traits higher concordance rates for those who are genetically similar indicate a fairly high degree of heritability for schizophrenia the fact that the highest concordance rates are around 50% indicates a fairly high degree of environmental influence as well Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 42 Research on the Heritability of Human Traits Diathesis-stress model another example of genotype / environment interaction: Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 43 11

12 Diathesis-stress model of schizophrenia Genetic predisposition (diathesis) No Yes Experience of environmental triggers (stress) No Normal Normal Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 44 Yes Normal Schizophrenic Research on the Heritability of Human Traits Intelligence: Correlation coefficients for the IQ scores of people with varying degrees of genetic relationship: Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 45 12

13 Correlation of IQ scores by genetic relationship and rearing environment Identical twins Fraternal twins Half siblings Adopted siblings Relationship Non-twin biological siblings Biological parent and child Adoptive parent and adopted child Reared Together Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 46 Reared Apart Research on the Heritability of Human Traits The higher the genetic relatedness, the higher the correlation of IQ scores, indicating a fairly high heritability of IQ Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 47 13

14 Research on the Heritability of Human Traits Correlations also show environmental influence: Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 48 Correlation of IQ scores by genetic relationship and rearing environment Identical twins Fraternal twins Half siblings Adopted siblings Relationship Non-twin biological siblings Biological parent and child Adoptive parent and adopted child Reared Together Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 49 Reared Apart

15 Research on the Heritability of Human Traits In each group, those reared together are more similar than those reared apart Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 50 Correlation of IQ scores by genetic relationship and rearing environment Identical twins Fraternal twins Half siblings Adopted siblings Relationship Non-twin biological siblings Biological parent and child Adoptive parent and adopted child Reared Together Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 51 Reared Apart

16 Research on the Heritability of Human Traits Those with more shared experiences more similar than those with fewer Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 52 Correlation of IQ scores by genetic relationship and rearing environment Identical twins Fraternal twins Half siblings Adopted siblings Relationship Non-twin biological siblings Biological parent and child Adoptive parent and adopted child Reared Together Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 53 Reared Apart

17 Research on the Heritability of Human Traits Those who shared prenatal environment more similar than those who didn t Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 54 Toledo Blade Friday, January 18, 2008 Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 55 17

18 Research on the Heritability of Human Traits Sources of variation between a clone and an adult donor: genetic: probably genetically identical possible mutations in the donor genes adult DNA in the embryo environmental: prenatal household/parents shared experiences cohort effects Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 56 Correlation of IQ scores by genetic relationship and rearing environment Identical twins Fraternal twins Half siblings Adopted siblings Relationship Non-twin biological siblings Biological parent and child Adoptive parent and adopted child Reared Together Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 57 Reared Apart

19 Research on the Heritability of Human Traits Some traits are more heritable than others In general, physical traits show high heritability intellectual traits show moderate to high heritability personality traits show low to moderate heritability Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 58 Cautions in Interpreting Heritability Statistics These estimates: DO NOT apply to individuals DO NOT apply to average differences between groups Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 59 19

20 Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 60 Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 61 20

21 Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 62 Cautions in Interpreting Heritability Statistics tell us nothing about how much the trait can be modified by environmental intervention can vary depending on the amount of environmental variation in a particular group Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 63 21

22 Any Questions on Chapter 2 and Chapter 8 (pp )? Lecture: Behavior Genetics (Ch 2 and Ch 8 pp ) - slide # 64 22