Gene-sex interaction in Hypercompetitive Attitude suggests beneficial effect of the DRD4 7-repeat allele in adaptation.

Twin studies provide evidence for the heritability of social attitudes, e.g. competitiveness, however, there are no psychogenetic association results linking competitive attitudes to genetic polymorphisms. Candidate gene studies report association with competitiveness-related phenotypes, risk taking for example was linked with the 7-repeat allele of the dopamine D4 receptor gene. This polymorphism has been studied extensively with novelty seeking and certain psychiatric disorders, as it plays a crucial role in molecular genetic mechanisms driving behavioral responses to the environment, especially modulating behavior through the reward circuitry. In the present study, we examined association of the DRD4 48-bp VNTR and competitiveness using self-report data from 399 non-related Caucasians. We found an interesting gene-sex interaction: 7-carrier males were more hypercompetitive as compared to non-carriers, while 7-carrier females were less hypercompetitive as compared to non-carriers. This finding remained significant after Bonferroni correction for multiple testing. Interestingly, among females we observed a significant positive correlation between hypercompetitiveness and mood characteristic variables, however, no such relationship could be detected in males. In 7-carrier females the association of hypercompetitiveness and anxiety or depression was more robust as compared to non-carrier females. These results highlight the importance of cultural influences in interpreting gene-sex interaction effects. Our results underlies interaction between genes and the environment; suggesting that the 7-repeat allele plays an important role in adaptivity, enabling sex-specific behavior to social expectations.