compared to A-carriers. In contrast, at high levels of peer delinquency, adolescents with the risk genotype, GG, had greater rates of externalizing behavior compared to A-carriers. The lower and upper bounds of regions of significance were −9.60 and −0.25, respectively. This indicates that these two regression lines were significantly different for all possible points when the score of peer delinquency was lower than −9.60 (outside of the range of responding) or higher than −0.25 (represented by the shaded area in Fig.1). This suggests that it is only at average to high levels of peer delinquency that the regression lines for A-carriers and those with the GG genotype differ significantly in terms of externalizing behavior.
