The one night stand gene?

An amusing article in a recent PLoS One by Garcia et al makes me wonder whether we soon may be requiring prospective mates to reveal not only their HIV status but also the number of tandem repeats in their dopamine receptor gene. Genetic tweaking of the receptor for the "feel good" neurotransmitter dopamine may be all it takes to ramp up sexual promiscuity and infidelity (usual disclaimer: This does NOT mean we are talking about a 'gene' for promiscuity, in spite of the title of this post). They rounded up 181 college students, asked them to answer a questionnaire about their sexual habits along with other proclivities, such as cigarette smoking and the tendency to take risks.  They also measured variable number tandem repeats (VNTR) polymorphism in exon III of the subjects dopamine D4 receptor gene (DRD4), which has been correlated with an array of behavioral phenotypes, particularly promiscuity and infidelity. They found that subjects having at least one 7-repeat allele (7R+) report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a “one-night stand”) and report a more than 50% increase in instances of sexual infidelity. (Genotypes were grouped as 7R+ (at least one allele 7-repeats or longer) or 7R- (both alleles less than 7-repeats); the 7R+ genotype was present in 24% of the sample.)