A new sex study has mapped out the sexual relationships of a typical US high school and come up with a startling rule that governs the intricate and intimate acts: "a girl is loath to date her old boyfriend's new girlfriend's old boyfriend."
According to the Web site LiveScience, the research was conducted by James Moody, a professor of sociology at Ohio State University.
The study found a relatively low number of teens who shared multiple partners, possibly because of the above-mentioned rule.
Thus, the map of romantic and sexual relationships revealed that students were connected by long chains rather than in a tight network bound by promiscuous groups.
Although common sexual partners were rare, it happened often enough to link hundreds of students together -- ?offering researchers valuable insights to help combat the spread of sexually transmitted diseases.
"We went into this study believing we would find a core model, with a small group of people who are sexually active," Moody said.
"We were surprised to find a very different kind of network," he said.
The map was based on the National Longitudinal Study of Adolescent Health, a 1995 survey of students at an unidentified Midwestern high school.
The students were mostly white, in the only public school in a mid-sized city more than an hour away from a metropolis. Over 830 of the school's 1000 students identified their sexual and romantic partners over the previous 18 months.
Just more than half reported having sexual intercourse, a rate comparable to the national average, the researchers say.
The largest chain encompassed 52 percent of the romantically involved students.
"Many of the students only had one partner," Moody said. "They certainly weren't being promiscuous. But they couldn't see all the way down the chain."
There were also 63 pairings involving two students who had not partnered with anyone else.