Maybe Monogamy Isn't For Humans After All

Although "I couldn't help it - I had a biological predisposition to cheat" might not be an acceptable excuse for your partner, scientists do believe that there is an ancient adaptive reason to have multiple sexual partners. In fact, a Swedish study of 552 men has pinpointed a potential set of genes in the vasopressin system that could predict how likely someone is to be an adulterer.

For men, the motivation is to double the amount of your DNA that is spreading into the next generation and potentially generations to come. For women, having children with an additional man means extra protection for herself and her children, even providing insurance if her primary partner dies.