why men cheat

A new study found a "cheating" allele present in both human and vole males. Those men with the cheating allele were more prone to marital dysfunction and more likely to get divorced. Men with two copies of the allele were twice as likely as a man without the allele.

The Karolinska Institute in Stockholm, Sweden, studied the genetics of cheating. Researchers said the cheating allele regulates the activity of a hormone in the brain that can affect a man's attitudes toward fidelity and monogamy.

If a man lacks the gene variant they're more likely to be a devoted mate, researchers said.

The study of 1,000 hetero couples focused on men because the hormone produced by the gene is known to play a larger role in men's brains than in women's brains.