Three studies have examined MAOA-related GxE with respect to drinking behaviors. Nilsson and colleagues studied two small samples of young adults from Sweden to investigate interactions among MAOA and psychosocial adversity (quality of family relations and childhood maltreatment) on alcohol-related problem behavior. Males with childhood maltreatment and the low-activity MAOA variant had more alcohol-related problems (median = 19.0) than males with the high-activity variant (median = 6.5), and males with no history of childhood maltreatment regardless of MAOA (low-activity, median = 3.0; high-activity, median = 1.5). There was no GxE associated with family relations (Nilsson et al., 2007). A different pattern of findings was observed for females, for whom psychosocial adversity was associated with a greater number of alcohol-related problems among females homozygous for the high-activity MAOA variant (median = 3.0), compared to carriers of the low-activity variant (median = 2.0) and those without exposure to psychosocial adversity (median = 2.0 and 0.0, respectively, among those homozygous for the high-activity variant and carriers of the low-activity variant) (Nilsson, Wargelius, Sjöberg, Leppert, & Oreland, 2008). In a sample of American Indian
