Lies, heartbreak, deception, disgrace and tears. Breakup sex. More tears and more breakup sex. Such is the typical narrative of a couple torn apart by infidelity. We see this frequently in our consulting rooms.
While we may be conditioned to think of the unfaithful heartbreakers among us as cold hearted narcissistic personalities, science has come up with a different take on the cheating phenomenon: Some people are genetically more predisposed to cheat than others.
Science takes an evolutionary journey, saying humans are members of the elite 3% or so of mammals that mate for life. Despite this hardwired tendency towards monogamy, cheating runs rampant on college campuses, in corporate offices, on business trips and on hacked cheater websites like Ashley Madison.
So if we’re genetically predisposed to stay monogamous, why do an estimated 22% of adults admit to having cheated on their current partners?
“The gene coding for a dopamine receptor plays a key role in cheating for men and women,” the scientists says. “Sometimes called ‘the happy hormone,’ it’s released after pleasurable activities like exercise, eating food and orgasming.”
There is a long and a short allele version of the dopamine receptor gene, and a 2010 study found that of the two variations, 50% of people who possess the long version have cheated on their partners, as compared to only 22% of their short allele counterparts.
The hormone vasopressin, which is associated with feelings like “trust, empathy and social bonding,” also plays a role in whether you’re more likely to cheat on your partner. According to the study, people with low levels of vasopressin are less likely to have high levels of empathy for their partners, thereby making them more likely to cheat.
There are also factors beyond genetics that increase the likelihood of infidelity, such as discrepancies in partner earnings (the wider the income gap, the more likely it is that your partner will be unfaithful, according to a 2015 study) as well as emotional baggage from past relationships.
That said, these findings should be taken with a grain of salt. Even if some humans are more genetically predisposed too infidelity than others, that doesn’t mean they should be absolved of all responsibility for their actions. Furthermore, as any good researcher knows, correlation does not equal causation, and just because your partner has lower levels of a certain hormone or makes more money than you do doesn’t mean they’re necessarily going to get it on with someone else.