Just about everyone out there has a story about infidelity, either in their own relationships or marriages, or in among their family and friends. The stories are invariably filled with pain and loss. Given that the costs are so great, and the risks so high, why are so many driven to cheat?

Research suggests that the causes are evolutionary. For men, this is easy to see. Men are driven to procreate with as many females as possible. For females, the reasons are more complex. However, a clue can be gained from the discovery that women are the most likely to cheat on their husbands on the day of the month that they are most fertile.

This suggests a two-sided motivation for women that has long been suspected by researchers. Women want two things for their offspring - the best genes possible, and security for them to grow to adulthood safely. For the latter, women find and marry a nice, stable, employed man who can provide for a family. But they may cheat with the strapping, handsome, but broke bad-boy in order to get the best genes possible.
It's the evolutionary equivalent of having your cake and eating it, too.
Still, human have many instinctive urges that are routinely put aside for the sake of a civilized society. It stands to reason that the urge to cheat may be put aside as well. But how? The consequences are terrible and often life-long, yet they have not been sufficient to deter it. Research suggests that adultery is in fact on the rise in America.

Perhaps the best solution is a cultural one. We would do well to study cultures where the rates of adultery are low, and see what they have to teach us about holding our families together.