While there were no main effects of rhCRH genotype on the Curious/Bold response to an unfamiliar intruder (F(1,105)=1.13, P = 0.29), -2232 C/G genotype strongly interacted with sex (F(1, 105) = 10.4, P = 0.002) to influence this type of response, accounting for 8% of the total variance. Males that were carriers of the G allele exhibited significantly increased levels of Curious/Bold responding when presented with an unfamiliar male, compared to C homozygotes (Figure 4B, Tukey-Kramer, P < 0.05), while no such differences were observed among females (n.s.). This remained true following rank-transformation of the data (F(1,105) = 8.3, P < 0.005). There were no main effects of genotype nor were there interactions among genotype, age and sex on the other reactivity dimensions.
