Good Excuse, or Is There Actually a Cheating Gene?

根据许多研究，草原田鼠的大脑中有更多的受体，用于一种称为加压素的激素，据信这在配对键合中起关键作用。忠实的草原田鼠不仅比作弊的表亲更具这些受体，而且受体位于大脑的一部分，它更接近奖励中心。

So when prairie voles mate, their bodies produce vasopressin, which causes their brains to reward the vole couple with a flood of pleasurable emotions, sealing the social bond. The brains of montane voles, on the other hand, have far fewer vasopressin receptors and therefore make much weaker connections between pair bonding and pleasure. So it's on to the next conquest.

The location and sensitivity of hormone receptors is dictated by our genes, which naturally leads to the question, could the urge to cheat on our romantic partners be partly a product of our genes? Are some of us walking around with prairie vole brains and others are stuck with the wandering eye of a montane vole?

关于不忠和一夫一妻制的根源的真实故事比您是否拥有“作弊基因”要复杂得多。人类的性行为是无数影响和互动的产物，从我们与父母的早期关系到围绕性行为的社会规范到我们的遗传倾向。

"We're never prisoners of our biology," says Justin Garcia, an evolutionary biologist and sex researcher at the pioneeringKinsey Instituteat Indiana University. "But it does explain why some people wake up with somewhat different motivations in these areas than other people."

The influence of these different genetically based "motivations" is difficult to quantify, but a2014年研究by Australian researcher Brendan Zietsch offers some intriguing clues. Zietsch surveyed the sexual habits of nearly 7,400 twins and siblings in Finland and found that 9.8 percent of men and 6.4 percent of women had more than one sexual partner in the past year.

But the fascinating finding was that the sets of identical twins — with identical genomes — reported the same exact levels of fidelity, while fraternal twins and regular siblings didn't. That indicates that variations in genes are powerful enough to influence sexual behavior beyond other environmental factors. In fact, Zietsch put a number on it: Our genes account for roughly男性不忠的63％，女性40％。

Vasopressin isn't the only hormone that's been linked to varying levels of monogamy and infidelity.Oxytocinis another hormone released during sex (and also during childbirth and nursing) that strengthens social bonds, and female voles with more oxytocin receptors are also more likely to mate for life.

Garcia at the Kinsey Institute conducted a landmark study of dopamine receptors and sexual straying. It's long been established that people with fewer or weaker dopamine receptors engage in riskier behavior — drug and alcohol abuse, and gambling — to get the same dopamine rush that the average person might get from eating a Snickers.

加西亚测试了181名参与者，其中一些参与者携带了多巴胺受体的较弱的D4变体。他发现，具有D4受体的人报告性不忠行为的可能性要高出50％。当他看着所有在研究中作弊的参与者时，患有D4受体的人更有可能多次这样做。

For Garcia, the genetic evidence points to a more nuanced understanding of what it means when somebody cheats in a relationship.

"The classic explanation is that they're not really in love," says Garcia. "But maybe they're more motivated by other feelings of sensation, risk and novelty."

最初出版：2017年12月20日