ALEX CHADWICK, host:
Back now with Day to Day. What is wrong with men anyway? Why don't they commit? Brothers, it is not our fault, or not entirely, for some of us, anyway. A new study published by the National Academy of Sciences says it's in our genes. And you can believe this study because it involves rodents. Reporter Nell Greenfieldboyce is here from the vaunted NPR Science Desk. Nell, what about this gene?
NELL GREENFIELDBOYCE: It's a gene associated with a brain hormone named vasopressin. And scientists got interested in it back when they were studying rodents called voles. You might have seen this if your cat brought them in. They're like little mice-like things that live out in the meadow. And some species of them are monogamous, while some aren't.
And so a few years ago, scientists found that, if they took this gene from a species of vole that was monogamous, the prairie vole, and they put it into another kind of vole, the meadow vole, suddenly, they could make the meadow vole bond to its mate in a way it hadn't before. And this got a lot of attention, and reporters immediately dubbed this the monogamy gene.
CHADWICK: And this gene is present in humans, or something like it. And so there's speculation about how it might apply to us.
GREENFIELDBOYCE: Yes, there was immediately speculation, and the researchers who did the original vole work say they get a lot of calls around Valentine's Day from people wanting to know if this was at work in men, too. But there hadn't been any studies until this new one.
A group in Sweden looked at this gene in hundreds of men, and they also looked at the men's answers to a bunch of questions. So things like how often do you kiss your wife or significant other? How often do you or your wife go out and do things together, you know, have interests outside the family?
CHADWICK: So what did they find?
GREENFIELDBOYCE: Basically, they found that men with one particular variant of this gene were more likely to score lower on this test. And what's more, they found that men with two copies of this gene variant were twice as likely to say that they'd had a marital crisis or threats of divorce in the last year.
CHADWICK: Now, is that statistically pretty significant?
GREENFIELDBOYCE: It was statistically shown to be real. It wasn't a huge effect. It was a small effect, a small association, but according to their study, it was real. Now that said, some researchers I spoke with said that they'd want to see this repeated by another group, just to make sure that there actually is this link.
CHADWICK: So how useful, really, is this info for a woman thinking about any particular man? Should she really ask now for some kind of gene analysis, or at least wonder about it?
GREENFIELDBOYCE: Yeah, I don't think you're going to see would-be brides taking their man into genetic testing clinics for this anytime soon, for a bunch of reasons. One, this gene, even though they found this association by looking at groups of men, it wasn't predictive for any one individual man. So that means, in this study, you had men who had the gene variant who didn't show any marital trouble at all. And meanwhile, you also had men who seemed to have some marital trouble who didn't have the gene. So you can't look at this gene for any one man and be able to make a prediction about what his relationship is going to be like.
Another thing to consider is, yeah, they found an association, but it was a modest one. And when you think about human relationships and all the things that go into human relationships, the effect of any single gene is going to be really, really small compared to a lot of other things that you could find out just by talking to the guy instead of looking at his DNA.
CHADWICK: NPR's Nell Greenfieldboyce on a new study published by the National Academy of Sciences on men and genes and relationships. Nell, thank you.
GREENFIELDBOYCE: Thanks very much.
MADELEINE BRAND, host:
Here's the thing. How many guys, if you could test for that gene variant, how many of them would really want to be tested for it?
CHADWICK: Well, I, you know, we're all open to exploring our relationships.
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