The primary hypothesis that youths' 5-HTTLPR genotype would interact with parenting to predict youths' positive affect levels was tested with ordinary least squares regression analyses. The main effects of child genotype (5-HTTLPR) and the measures of positive parenting, as well as their interaction, were entered to predict youths' positive affect. In Studies 1 and 3, the effects of the L'S' and S'S' genotypes were tested against the effect of the L'L' genotype. In study 2, the effect of the S'S' genotype was tested against the effect of L' carriers, because L'L' genotype consisted of a too low number of participants (N=39) to be used as reference category. As shown in the Table 1, the interaction of 5-HTTLPR with positive parenting significantly predicted youths' positive affect in all the three studies. Neither gender nor ethnicity moderated this GxE.
