We repeated the ANOVA in the subgroup of healthy volunteers (N = 145) to exclude that the G×E interactions we found were due to the inclusion of psychiatric patients in our sample and were not generalizable to the population at large. The results for the subgroup of healthy volunteers were identical to those for the entire sample. We found significant main effects of gender (F1,137 = 37.53, P<0.0001) and ETLE (F1,137 = 10.34, P = 0.002), no main effect of MAOA genotype (F1,137 = 0.86, P = 0.35), and significant interaction effects for MAOA×ETLE (F1,137 = 10.13, P = 0.002) and for gender×MAOA×ETLE (F1,137 = 6.66, P = 0.01). The cumulative variance in the physical aggression score explained by the ANOVA effects involving the MAOA allele was 12.1% (Table 3).
