The Biology Behind Cheating

Photographed by Lauren Perlstein.
Why do people cheat? There are several reasons why we take such a risk. It could be something about ourselves (perhaps our self-esteem), something about our relationships (perhaps they're not satisfying or fulfilling), or something about the situation (maybe we just had the chance). However, infidelity or cheating could also result from, at least partially, underlying biological and hormonal influences. For example, men with higher testosterone have more interest in having sex outside of their relationships, which is the same thing as cheating if your partner does not condone it. Similarly, women with higher levels of estrogen are more likely to cheat. Though these studies focused on different-gendered couples it is likely that within same-sex couples, those with higher testosterone or estrogen would be more likely to cheat.

Even though we don’t carry around testosterone- and estrogen-testing kits to use on our partners (that would be cool, though, wouldn’t it?), we can determine people's levels of these hormones without even realizing it. How? By listening to our partners’ voices. Men with greater testosterone have deeper voices, while women with more estrogen have higher voices. In one study, participants listened to audio clips of male and female voices that had been digitally altered to be higher or lower in pitch; then, participants indicated how likely they thought each person would be to cheat, based on his or her voice alone. Participants rated men with deep voices and females with high voices as more likely to cheat than men with high voices or women with deep voices. And, it turns out they were pretty accurate; the same hormone levels that influence our voice pitch influence our tendency towards infidelity.

This might make it sound like certain people can’t help but cheat — that we are at the mercy of our hormones. However, that's not what the research shows. If biology were destiny, then every high-testosterone male and high-estrogen female would be a serial cheater, which clearly isn’t the case. Rather, hormones may make resisting temptation harder, but people still have the ability to be self-aware and self-reflective — and thus should be held accountable for their own choices. 

Portions of this article were adapted from the Science of Relationships book. If you’d like to learn more about our book, please click here (or download it here). Interested in learning more about relationships? Click here for other topics on Science of Relationships. Like us on Facebook or follow us on Twitter to get our articles delivered directly to your NewsFeed.