The interplay of genetic influences and social processes in developmental theory: Specific mechanisms are coming into view

In the coming years we can look forward to research that clarifies specific mechanisms that account for the interplay between genetic and environmenta l influences on psychological development. Certain misconceptions, arising from research traditions initiated by Francis Galton on the one hand and G. Stanley Hall on the other, may now be set aside in the light of new eviden ce. Three important findings promise a new synthesis. First, while each of us is born with about 100,000 genes that, under ordinary circumstances, do not change, the expression of these genes on behavior is dynamic. Some gene tic influences are expressed early in development, but others are manifest many years later. Second, genetic factors often account not only for some o f the individual differences in the measures of adjustments we typically us e to monitor development but also for individual differences in environment al experiences that covary with those measures of adjustment. Indeed, genet ic factors have been found to account for a surprising amount of covariance between measures of the social environment and of adjustment in young chil dren, adolescents, and adults. Third, the expression of genetic influences are very malleable and responsive to the social environment. These new find ings are revealing specific mechanisms for the interplay of genetic and soc ial environmental factors in four domains. First, the social environment ma y play both a necessary and specific role in the expression of particular g enetic influences on a range of behaviors from depression to social respons ibility. Second, an understanding of the interplay between the social envir onment and genetics may lead to a clearer definition of the phenotypic mani festations of particular genetic influences. Third, we will-as a result of these studies-have a clearer fix on the timing of important events and thei r sequence in development. Fourth, this new genre of work promises to illum ine more completely mechanisms by which the social environment influences d evelopment independent of genetic influence.