London - It might seem like the perfect get-out clause for those with a roving eye: some people just aren’t built to be faithful.
Scientists have found a gene that raises the odds of cheating on a partner.
They say that when a man or woman with the “love rat gene” has an affair, they receive the same chemical rush as a gambler whose luck has changed or an alcoholic savouring a drink.
Researchers quizzed 180 young men and women about their attitude towards relationships and tested them for a gene called DRD4, which affects levels of the brain chemical dopamine. The one quarter or so with the “love rat” version of the gene were more than twice as likely to be unfaithful. And when they did cheat, they had more one-night stands, the journal “PLoS ONE” reports.
Researcher Justin Garcia said: “What we found was that individuals with a certain variant of the DRD4 gene were more likely to have a history of uncommitted sex, including one-night stands and acts of infidelity.
“The motivation seems to stem from a system of pleasure and reward, which is where the release of dopamine comes in.
“In cases of uncommitted sex, the risks are high, the rewards substantial and the motivation variable - all elements that ensure a dopamine ‘rush’.”
He added that his results suggest it is possible to feel committed for a partner, but still feel the need to cheat on them.
But those with a wandering eye cannot wholly blame their genes.
Garcia, of the State University of New York, said: “The study doesn’t let transgressors off the hook. Not everyone with this genotype (genetic make-up) will have one-night stands commit infidelity.”