Parenting intervention effects on children's externalizing behavior The moderating role of genotype and temperament

Recent research suggests that children's heightened susceptibility to parenting may have a (poly)genetic basis, and may be grounded in children's temperament. However, much current evidence is of a preliminary—correlational—nature. Because in correlational designs alternative explanations for gene–environment (G × E) or temperament–environment (T × E) interactions cannot be discounted, it is pivotal to conduct experimental studies in which parenting is actively manipulated. Based on data from a recently conducted randomized trial (n = 387) of the Incredible Years parenting intervention, experimental evidence is provided for G × E and T × E interactions in an at-risk population of children aged 4–8 years. The discussion centers around the use of polygenetic data and microtrial designs, and provides suggestions for how to integrate endophenotypes in tests of G × E and T × E.