COSTA RICA CONFIDENTIAL — You may be genetically predisposed to cheat. A recent study by researchers at Binghamton University, State University of New York has revealed that about half of us inherited a gene that makes us more likely to have one-night stands and to stray if we are in an ostensibly monogamous relationship.
The culprit? A little gene called DRD4.
When you carry a variant of that gene, which is a dopamine receptor, you are more likely, according to researcher Justin Garcia, “we already know that while many people experience sexual activity, the circumstances, meaning and behavior is different for each person,” said Garcia. “Some will experience sex with committed romantic partners, others in uncommitted one-night stands. Many will experience multiple types of 
sexual relationships, some even occurring at the same time, while others will exchange sex for resources or money. What we didn’t know was how we are motivated to engage in one form and not another, particularly when it comes to promiscuity and infidelity.”
That same gene appears to make us want to hit the bottle and the blackjack table. Dopamine is involved in the brain’s pleasure and reward system. In cases of uncommitted sex, the risks may be high but the rewards are high, too, which can produce a big ol’ dopamine rush.
Gathering a detailed history of the sexual behavior and intimate relationships of 181 young adults along with samples of their DNA, Garcia and his team of investigators were able to determine that individual differences in sexual behavior could indeed be influenced by individual genetic variation.
The study may shed some light on why some people report feeling very much in love with and attached to their partners, yet still commit acts of infidelity.
“What we found was that individuals with a certain variant of the DRD4 gene were more likely to have a history of uncommitted sex, including one-night stands and acts of infidelity,” said Garcia. “The motivation seems to stem from a system of pleasure and reward, which is where the release of dopamine comes in. In cases of uncommitted sex, the risks are high, the rewards substantial and the motivation variable – all elements that ensure a dopamine ‘rush.’”
According to Garcia, these results provide some of the first biological evidence that at first glance, seems to be somewhat of a contradiction: that individuals could be looking for a serious committed long-term relationship, but have a history of one-night stands. At the same time, the data also suggests it is also reasonable that someone could be wildly in love with their partner, commit infidelity, and yet still be deeply attached and care for their partner. It all came back to a DRD4 variation in these individuals. Individual differences in the internal drive for a dopamine ‘rush’ can function independently from the drive for commitment.
“The study doesn’t let transgressors off the hook,” said Garcia. “These relationships are associative, which means that not everyone with this genotype will have one-night stands or commit infidelity. Indeed, many people without this genotype still have one-night stands and commit infidelity. The study merely suggests that a much higher proportion of those with this genetic type are likely to engage in these behaviors.”
A detailed report can be found in the current issue of Public Library of Science’s PLoS ONE journal. The article, “Associations between Dopamine D4 Receptor Gene Variation with Both Infidelity and Sexual Promiscuity,” can be found at http://dx.plos.org/10.1371/journal.pone.0014162
