In conclusion, we find evidence that CHRM2 is associated with different developmental patterns of externalizing behavior from early adolescence through young adulthood, and further demonstrate that the effect of this gene on externalizing trajectories can vary as a function of exposure to antisocial behavior within one’s peer group. These analyses underscore the importance of studying genetic influences across development, and of identifying environmental factors that moderate risk. In terms of future directions, we suggest that the ultimate goal of this work should be to inform the design and implementation of effective prevention/intervention programming for individuals predisposed to the development of problematic externalizing profiles. Realistically, however, these findings are most likely to represent incremental progress in a much longer process of characterizing the complex mechanisms by which specific environmental factors moderate the risk associated with identified genes, and vice versa. Regarding CHRM2, much work remains to be done in terms of articulating the mechanisms of cause and effect, and it would be irresponsible to suggest otherwise. Thus, empirical efforts should remain our focus until such a time as the clinical utility of these basic research findings can be more fully realized.
