Several limitations of the present research should be noted. First, only one genetic polymorphism was examined, which does not represent all the genetic variation that conceivably could place youth at risk for health-compromising behaviors. Many genetic variants may alter risk, the expression of which may emerge only in particular environmental contexts. A corollary of this limitation is the perception that genes confer only risk. Genetic effects may also be protective, and that which is conceptualized as a risk-promoting genetic effect may actually be the absence of protective effects. Second, the long-term follow-up assessment described in this paper, conducted 2 years after the intervention ended, included only young adolescents. As we continue to follow the sample, we will be able to determine if the G×E findings carry forward throughout adolescence and early adulthood.
