The prevalence of conduct disorder (CD) is consistently higher in males than females (Simonoff et al. 1997; Steiner, 1997; Eley et al. 1999; Farrington & Loeber, 2000; Loeber et al. 2000; Moffitt et al. 2001a; Jacobson et al. 2002; Maughan et al. 2004) despite similarities in exposure to environmental risk factors, co-morbidity patterns and age of onset (Herrera & McCloskey, 2001; Moffitt et al. 2001a; Ilomaki et al. 2006). However, when stratified by a genetic risk factor, gender differences may arise in the patterns of exposure to risk factors. Thus, the study of gene-environment interaction (G × E) for CD by gender could elucidate the etiology of gender differences for this outcome.
