Does Size Matter? And Other Sex Myths

So the next time you're tempted to rob the cradle, it might be wise to keep your pants on. "People in their late teens are not good lovers," says Laumann. "The ability to form and maintain relationships comes later."

Do Men Have Stronger Sex Drives Than Women?
According to Berman, it's common for women to have lower libidos than men. But men, too, experience a loss of desire—"especially those in their mid-to-late 40s and beyond," she says.

Laumann adds that lower sex drives in women may be rooted in evolution: to protect themselves from predators, it was essential to avoid the vulnerable state of pregnancy. But for men, sex is less costly. "The majority of men think about sex every day. But only 25 percent of women think about it every day," he says. "Sex for men is less complicated. They tend to act on their urges."