But they've found the drunk/gambling/horror/liberal/slut/cheater gene:
A particular version of a dopamine receptor gene called DRD4 is linked to people's tendency toward both infidelity and uncommitted one-night stands, the researchers reported Nov. 30 in the online open-access journal PloS One. The same gene has already been linked to alcoholism and gambling addiction, as well as less destructive thrills like a love of horror films. One study linked the gene to an openness to new social situations, which in turn correlated with political liberalism.
In the new study, researchers gathered a detailed history of sexual behavior and relationships from 181 young adults. They also collected DNA samples from the volunteers' cheeks and analyzed the samples for the presence of the thrill-seeking version of DRD4. "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," study researcher Justin Garcia, a postdoctoral fellow at Binghamton University, State University of New York, said in a statement.
People who have the DRD4 gene were twice as likely to have a history of one-night stands and a little more than twice as likely to have committed adultery. The adultery stat is interesting: 50% of people in the study with DRD4 told researchers that they had committed adultery, compared with 22% of those who didn't have the gene. But since this particular gene is associated with risk-taking, and since admitting to a researcher that you've committed adultery could feel like a risk all by itself (what if it got back to the person you cheated on?), it seems reasonable to assume that people with DRD4 aren't just more likely to commit adultery; they would also be more likely to admit to having committed adultery. And people who don't have the risk-taking gene aren't just less likely to have committed adultery; they're less likely to admit to having committed adultery. So that 22% figure could underestimate the number of non-DRD4ers out there who've fucked around on their spouses.
Finally, this quote from one of the researchers is kind of annoying:
"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."
I don't think Garcia meant to lump people who have one-night stands in with adulterers. But just in case he did: There's nothing transgressive about having a history of one-night stands. No one is transgressed against when two single people have a one-night stand so there's no hook that one-night-standers need letting off of.