Several of the environmental factors that have been examined in G × E studies for conduct disorder (e.g., parenting, deviant peer affiliations), as well as other known risk factors for poor behavioral and emotional health outcomes in general are also genetically influenced to some degree (Kendler and Baker, 2007; McAdams et al., 2013). This raises the possibility that one’s genetic predisposition for conduct disorder may be correlated with environmental exposures for conduct disorder through the process of gene-by-environment correlation (rGE). There are multiple mechanisms that may result in a correlation between an individual’s genotype and environment, including evocative gene-environment correlation (where an individual’s heritable behavior elicits a particular environmental response); active gene-environment correlation (where an individual’s genetic predispositions lead them to seek out particular environments), and passive gene-environment correlation (where the type of environment provided to a child is correlated by his/her inherited genotype because biological parents provide both genetic material and a rearing environment for their offspring) (Scarr and McCartney, 1983). With respect to conduct disorder, there is retrospective longitudinal evidence that males select into peer groups whose level
