DRD2 and alcohol drinking: We based expected effect sizes (R2) of the interaction between a DRD2 and stressful environments on the severity of alcoholism (R2 = 0.07) [23], main effect of the DRD2 genotype on problematic gaming (R2 = 0.11) [15], and main effect of interpersonal stressful environments on problematic gaming (R2 = 0.09) [21].