ASPD, or have violent crime convictions, than were males hemizygous for high-activity alleles. Importantly, this effect was observed only under conditions of childhood maltreatment, such that males with low-activity alleles were more sensitive to the detrimental effects of maltreatment than were males with high-activity alleles. These findings indicate a gene-by-environment interaction (GxE), whereby individuals with different genotypes exhibit varying levels of sensitivity to environmental conditions. Furthermore, recent evidence from a twin study indicates that latent genetic effects on externalizing outcomes can be more influential in the presence of environmental adversity (Hicks, South, Dirago, Iacono, & McGue, 2009). This may provide one explanation for why children’s long-term outcomes are differentially affected by the experience of maltreatment.
