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 call 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 centre 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.