MACCOBY of infonnation for measuring a trait. When children's of the children, from children's self-reports, or from teacher ratings. It appears that as more different from one another than other sources of

vary depending on the source characteristics are assessed through parents' ratings, heritability estimates are often considerably higher than when assessments are derived from behavioral observations see their children In twin and adoption studies, estimates of the power of environmental factors are derived by adopting the additive assumption, i.e. by assuming that that the sources of variation in a trait can be separated into independent genetic (G) and environmental (E) components that together (along with error variance) add to 100% of the variance be accounted for. On the basis of this assumption, the heritability coefficient can