Abstract
Although few would now contest the presence of Gene × Environment (G × E) effects in the development of child psychopathology, it remains unclear how these effects manifest themselves. Alternative G × E models have been proposed (i.e., diathesis-stress, differential susceptibility, bioecological), each of which has notably different implications for etiology. Child twin studies present a powerful tool for discriminating between these models. The current study examined whether and how parental involvement moderated etiological influences on attention deficit hyperactivity disorder (ADHD) within 500 twin pairs aged 6-11 years. Results indicated moderation of genetic and nonshared environmental contributions to ADHD by parental involvement, and moreover, suggested both differential susceptibility and bioecological models of G × E. Results highlight the utility of child twin samples in testing different manifestations of G × E effects.