How to Lower His Risk

Dr. Ley

Dr. Zak

Dr. Brizendine

Dr. Brizendine explains that scientists discovered that in prairie voles and humans, monogamous males have a long version of the vasopressin receptor gene, the gene that's been dubbed the "cheater gene." Males who have a shorter version tend to be the ones who are promiscuous.

Dr. Ley says, "The brain is about a third of it. Genes are about half of it. There's still stuff left. Biology is not destiny. It's a piece of it, but it doesn't control our choices."

"And the modifiable piece is Oxytocin," says Dr. Zak. "Oxytocin, we've found, is this bonding chemical that causes you to trust other people." Men who have a low number of Oxytocin receptors are less likely to form strong relationships and are at a higher risk to cheat.

Find out how to spot a possible cheater just by looking at his hand!


"This is a predictor, not just of sexual behavior, but lots of testosterone-related behavior, including aggression," Dr. Ley says.


Another physiological factor is if a male is well-endowed. That means more testosterone, and a higher risk for cheating. Dr. Amen remarks that women should think twice about wanting a man who's well-endowed.

Dr. Phil points out there are many factors that may explain why a man chooses to cheat on his loved one, including biological, social, physiological, cultural and environmental factors.

Dr. Brizendine agrees, adding, "How you're raised, what the ethics of your family are, how your father behaved … For women, to understand that this is what is running the train and running the engine is really helpful. It's not giving the guy a complete pass."

Dr. Ley also explains that facial symmetry is another factor. "One side of the face doesn't always entirely match. The more the same it is, the more it is an indicator to women that that man has high genetic value. Men whose faces are more [symmetrical] have a greater number of partners because more women want to have their children."

"So, great genes, but they may cheat on you later on," Dr. Zak points out.

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