Here's a piece of interesting information that I found from the Newscientist site:

[Population geneticist Michael] Hammer and his colleagues sequenced DNA from 90 people belonging to six groups: Melanesians, Basques, Han Chinese, as well as three African cultures: Mandenka, Biaka and San.

Hammer's team discovered more genetic differences in the X chromosome than would be expected if equal numbers of males and females tended to mate, over human history. The only explanation for this pattern is widespread, long-lasting polygyny, he says.

His team's analysis reflects all of human history, and modern monogamy has not even left a blip in our genomes. "I don't know how long monogamy has been with us," Hammer says. "It seems it hasn't been around long, evolutionarily."

Many of my friends do "stray," whether it be from their wives or their girlfriends. They do not necessarily have mistresses, but they do cavort with MPAs^?, GROs^?, and other PSPs^?.

So when one says that "playing the field" is considered "cheating," that person may be more hypocritical than you think.