C/G animals consumed more alcohol in the social group than did those with the C/C genotype (Figure 5, F(1,72) = 8.5, P = 0.005). Genotype accounted for 12% of the total variance in ethanol consumption, and a main effect of genotype remained after controlling for rearing condition (peer-reared vs. mother-reared) and sex (male vs. female) (F(1,66) = 5.04, P ≤ 0.03; C/C vs G, Tukey/Kramer, P < 0.05). It also remained following both statistical correction for testing cohort (F(1,66)=4.5, P ≤ 0.04) and rank transformation of the data (F(1,66) = 7.9, P < 0.007). In each of these analyses, G allele carriers exhibited higher levels of alcohol self-administration (Tukey/Kramer, P < 0.05).
