BehaviorGenetics.pptVIP

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Interactions between Genes and Environments Interactions between genes and environments modeled by Gottliebs bi-directional model. Tennis and testosterone: Loss affects behavior (slumping posture) psychological state (low self-esteem) neural activity in certain parts of the brain; the genes for testosterone are turned off. But the genes havent been changed by these events. When the person later wins a match, the genes may turn on again. Interactions between Genes and Environments: Gottlieb’s model Genes sometimes determine whether environment has an influence The developmental stage of the child affects whether the environment has an influence Example: Critical periods for the effects of teratogens on the fetus. Environmental influences are dependent on timing. Genetic systems determine when the environment may have an influence. Genes sometimes determine whether environment has an influence The developmental stage of the child affects whether the environment has an influence PKU: Effects of dietary intervention on PKU depend on when the intervention is attempted. Earlier intervention is more effective. Heritability Heritability: A statistical estimate of the contribution of genetic differences to phenotypic differences in traits, such as intelligence or personality. Traits with high heritability are mainly influenced by genetic differences: Most of the differences we see among? people are the result of genetic differences. Low heritability is the opposite: Most of the differences we see among? people are the result of environmental differences. Heritability may be different for different groups and under different environmental conditions. Heritability may change with age. (In general, genetic influence becomes stronger with age.) What would happen to heritability if everyone was raised in the same environment? Since there are no environmental differences, all of the differences