Dopamine transporter, gender, and number of sexual partners among young adults.

The dopamine transporter gene (DAT1) codes for a dopamine transporter protein, which limits the level and duration of dopamine receptor activation. The DAT1 gene is a strong candidate gene for reward-seeking behavior. This article reports compelling evidence for the association between the 40 bp variable number of tandem repeats in the DAT1 gene and the self-reported number of sexual partners among young adults in the United States using the sibling subsample of more than 2500 individuals who participated in the National Longitudinal Study of Adolescent Health. We performed tests of genotype-gender interaction as well as analyses stratified by gender. Among the males, possessing one or two alleles of the 10 repeat is associated with an 80-100% increase (P<0.0001, 2df) in the number of sexual partners as compared with the homozygotes for the 9 repeat. The association holds in race/ethnicity-stratified analyses, in Allison's procedure that tests population stratification, and in within-family fixed-effects models. Covariate adjustment for a standard set of socioeconomic factors including religiosity, family structure, parental education, marital and cohabitation history, and neighborhood poverty did not attenuate these associations. Discussion is provided why this finding is absent among females.