Subtitles section Play video Print subtitles Cheating on your significant other is taboo in almost all cultures, yet somehow adds flavor to the plot of movies and inspiration for countless songs about heartbreak. But why do people cheat in the first place? Is there a science behind it? Only about 3% of mammals are monogamous , meaning they stay with one partner their whole life and humans fall into this category. From an evolutionary perspective, it creates an advantage where one partner can protect the younglings while the other searches for food and provides resources. But somehow, extra pair-mating or cheating is a fairly common human behavior. The gene coding for a dopamine receptor plays a key role in cheating for men and women. Sometimes called the "happy hormone", it's released after pleasurable activities like exercise, eating food, and orgasming. And one study found that 50% of people who possess the long allele variant of this gene had cheated on their partner, compared to only 22% of people who have the short allele. The long allele participants also had a tendency to be risk-takers and succumb to addictive behaviors such as alcoholism. Perhaps the phrase once a cheater, always a cheater may have a basis in reality. Levels of the hormone vasopressin also play a role. Similar to oxytocin, which is sometimes called the "cuddle hormone" vasopressin can affect trust, empathy and social bonding. In fact, injecting vasopressin directly into a polygamous montane vole's reward center increases the likelihood of it becoming monogamous! People with autism also have lower vasopressin levels, affecting their ability to understand social cues. And in 2014 a study involving over 7000 Finnish twins found that cheating women had a variant in the gene that codes for a vasopressin receptor further suggesting that low levels of vasopressin have an influence on cheating. Money may also be a factor; males who earn significantly more than their female counterpart are more likely to cheat. But they're also more likely to cheat on their wives if they are stay-at-home dads. Only when both partners have similar earning potential do the chances of either cheating decrease significantly. Of course, many other life factors can lead to infidelity; from unresolved emotional issues, baggage from past relationships and...excessive alcohol intoxication. Unfortunately same-sex partnerships have not been studied enough to gain any clear insights, highlighting how scientific research continues to exclude specific minority groups. Either way, cheating is clearly based in biology and genetics for some of us, in spite of being a monogamous species. Special thanks to Audible for supporting this episode and giving you a free audiobook at audible.com/asap. This week we wanted to recommend the book "SuperBetter" where author and game designer Jane McGonigal explains how to cultivate greater resiliency in everyday life by using the mental strengths you apply to game-playing. You can get a free copy at audible.com/asap or any others of your choice from a massive selection! We love them as they are great when you're on the go. And subscribe for more weekly science videos!