Does the Slut Gene Exist?

Maybe there’s a gene for the belief that genes can explain everything.

If so, I’m missing it.

In the last seven days, we’ve been hearing a lot about the DRD4 gene, dubbed by the media as the “slut gene,” that supposedly explains why certain people are likely to have lots of sex, especially of the adulterous variety.

In a study published last week in the journal PLoS One, a group of researchers, led by Justin Garcia at Binghamton University in New York, took 181 undergraduate-aged subjects, asked them about their sex lives, and ran a DNA test to see which version of the DRD4 gene they had: the 7R+ or the 7R- kind. The DRD4 gene has made headlines before. In fact, it’s a goldmine of scandalous behaviors, linked to everything from alcoholism to impulsive financial decisions. It influences how our brains respond to dopamine, a feel-good neurotransmitter unleashed by new and rewarding experiences.

So the Binghamton group had good reason to think that they’d find something if they looked at its role in sexual behavior. And they did find something. But first, here’s what they didn’t find:

They didn’t find that those with one version of the gene had more sex than those with the other. And they didn’t find that the people with the so-called slut gene had more sexual partners, or that they're more likely to cheat.

What they found is that the group who had the 7R+ version was more likely to have had, at one point or another, “a one-night stand,” and that if someone with a 7R+ did cheat in a relationship, they were likely to have done so with more people than their 7R- counterparts.

The study leaves several questions unanswered. Was this 7R+ group really more likely to have had a one-night stand, or just more likely to report it? Did they actually cheat with more partners, or were they simply more willing to reveal the full extent of their adultery? You could just as easily interpret the study’s results this way and declare DRD4 the “candor gene.”

The DRD4 study isn’t an isolated case of shaky genetic science. In fact, it joins a cadre of questionable scientific assertions that link single genes to much broader patterns of behavior.

The last decade has witnessed an explosion in genetics studies, and with it, a proliferation of sensational study results that run the gamut from disingenuous pop-science to borderline science fiction. In the past 10 years, we’ve heard about the God gene that allegedly explains religiosity; the warrior gene that supposedly makes those who have it more aggressive when provoked; and the liberalism gene, a single gene that, we’re told, predisposes a person toward joining a particular political party.

We’re still expected to accept the idea that one blip of the brain can fully explain who we are and why we behave the way we do.

This cluster of discoveries smack of modern-day phrenology, the early 19th-century practice of groping someone’s skull in order to determine how well-developed were their various traits and capacities, whether a tendency toward violence, or a sense of satire. Today, phrenology is a dirty word. Yet with these studies granting such consequence to a single gene—a microscopic strip in our heads whose sole purpose in life is to manufacture one dinky little speck of protein—we’re still expected to accept the idea that one blip of the brain can fully explain who we are and why we behave the way we do.

Genes do play a role in determining each of our brains’ relationship with dopamine. Most of us like dopamine. Some of us love it. A few of us will trample anything that stands in our way to get it. DRD4 informs how anyone’s brain processes dopamine—and so do hundreds of thousands of other genes, yet to be determined, and the mysterious ways they interact with their environment.

“There are economists publishing papers saying whether you’re conservative or liberal is an inherited trait. It reminds me of the old eugenics trope which was, poverty is inherited. Well, of course!” says Misha Angrist, the author of a new book, Here Is a Human Being, about the recent medical craze for personal genomics.

Studies that play into the false belief that a single gene could explain or cause a behavior like promiscuity are, says Angrist, "a travesty.”

“I file it in that place in my brain where I keep things that may be worth knowing about and keeping in the back of my mind for future reference,” Dr. Paul Appelbaum, from the center for Human Genetics at Columbia University, said of his reaction to the DRD4 study. “But I know by now to be very careful about attributing too much significance to a report like that.”

Justin Garcia, who led the Binghamton research team, himself admits that the way his study is being portrayed isn’t entirely accurate. “The popular thing right now is the cheating gene, or the slutty gene, or the promiscuous gene, and it’s a little bit more particular than that.” Actually, it’s a lot more particular than that.

We might wish the matter were so simple, but the fact remains that there’s no such thing as a slut gene.

Slutty science, on the other hand? That we’ve got in spades.

Casey Schwartz is a graduate of Brown University and has a master's in psychodynamic neuroscience from University College London. She has previously written for The New York Sun and ABC News. Currently, she's working on a book about the brain world.