Forces of attraction

To come up with the list, Meston and Buss asked 444 men and women, age 17 to 52, to list reasons why they, or people they've known, have had sex. They then had 1,500 undergraduate students at UT-Austin rank the reasons on a one-to-five scale of how often they applied to their experiences.

Twenty of the top 25 reasons given were the same for men and women, and the No. 1 for both was "I was attracted to the person."
"I was surprised there wasn't a great gender difference," said Meston. "Women were more likely to say they wanted to express their love for the person, but they were very quick to also cite physical reasons and out-of-control hormones most people associate with men."

Meston, who is continuing to collect data for follow-up studies, acknowledged that college students' out-of-control hormones tilt the results. Future studies will focus on other age groups, ethnic groups and religious people. Metson said she also wants to find out about the outcome of sex for which people gave particular reasons.

Despite youthful answers like "the person was too hot to resist," Meston said she was struck that the college students gave some reasons that might offer lessons for people of all ages, such as that sex helped them get to sleep.

"For older couples in which the sex drive is mismatched, it might be instructive to learn that not everybody is having sex for pleasure," she said. "Nothing's wrong with you — you just might need to find your own reason for having sex."