Tests also were made for gender differences in the G×E hypothesis advanced. Although gender has been identified as an important source of variability in substance use and abuse among members of all racial and ethnic minority groups (Johnston et al., 2004), few empirical studies have explored gendered G×E effects. As expected, the hypothesized G×E effects emerged for male, but not female, adolescents. Two explanations can be offered for this finding. First, the rates of substance use for male adolescents were several times those of female adolescents throughout the study. Greater prevalence of substance use renders interactions easier to detect. A much larger sample than the one included in the present study may include female youths who engage in higher rates of substance use and permit an adequately powered test of the G×E hypothesis addressed in this study. Second, gender differences in substance use rates may reflect a tendency for male adolescents to turn to substance use as a coping tactic. It is also consistent with other studies in which male adolescents were found to be more likely than female youths to respond to life stress by losing inhibitory controls (Brody, Chen, et al., 2006; Hetherington, 1989; Rutter, 1990).
