Belsky & Pluess (2009) suggest that children with so-called “risk alleles,” i.e., genetic variations thought to be associated with adverse outcomes, may be more sensitive to the impact of parenting behavior than are children who do not have these alleles. Preliminary evidence with young children has lent considerable support to the hypothesis that variability at DRD4, a well-studied 48-base pair (bp) repeat in the coding region of the dopamine D4 receptor, may indeed contribute to differential susceptibility to parenting (Bakermans-Kranenburg, van IJzendoorn, Pijlman, Mesman, & Juffer, 2008; Bakermans-Kranenburg & van IJzendoorn, 2007; Belsky, Bakermans-Kranenburg & van IJzendoorn, 2007). Variation at DRD4 also has been studied as a risk factor for certain problems in childhood, including ADHD (Gizer, Ficks, & Waldman, 2009) and risk for substance use (e.g., Conner, Hellemann, Ritchie, & Noble, 2010). Based on the hypotheses that DRD4 would confer differential susceptibility to parenting influences in adolescence and that substance use would escalate during adolescence, we predicted genetic moderation of a parenting-based prevention program on substance use outcomes would emerge.
