As most every parent knows, hooking up for casual sex is bad for young people because it causes emotional or psychological damage.

Right?

Well, actually, no. At least not for young adults between the ages of 18 and 24, according to a new study by University of Minnesota researchers.

Even they found the results startling.

They asked more than 1,300 young Minnesota adults about their most recent sexual encounters, their self-esteem and their emotional well-being. Interestingly, only about one-fifth of the subjects said their last encounter was casual. But their overall emotional status was no different than the four-fifths who said they were in committed relationships with their most recent sexual partner.

"We were so surprised," said Marla Eisenberg, an assistant professor at the university's School of Public Health who studies adolescent and young adult health.

"The conventional wisdom is that casual sex, 'friends with benefits,' and hooking up is hurtful. That's what we've been teaching kids for decades," especially in the federally funded abstinence-only sex education programs, she said.

Not that Eisenberg advocates casual sex. Far from it.

"Casual sex is not for everyone" as an emotional matter, she said. Moreover, there is real physical risk: Rates of sexually transmitted diseases are rising relentlessly, and teen pregnancy rates in Minnesota are on the increase as well.

But, she said, sex education curriculums, parents and public health programs should "focus on the things that are real threats," such as interpersonal violence, pregnancy risk and STDs, not on the theory that casual sex is emotionally harmful.

The researchers surveyed 1,311 young adults in Minnesota, pulled from a group they began following years ago as part of a major ongoing research study in adolescent health and nutrition. All the people in the study were sexually active and answered a series of survey questions about their last sexual encounter, depressive symptoms and self-esteem.

The researchers divided the responses by how the subjects described their most recent sexual encounter. About 25 percent said it was with a committed partner, 55 percent said it was an exclusive dating partner, 12 percent said it was with a close, but not sexually exclusive, partner, and 8 percent said it was a casual acquaintance.

That breakdown fits with other similar surveys of young adults, Eisenberg said.

But what was different is that they found no differences in reports of depression or self-esteem, regardless of gender or the type of most recent sexual encounter, she said.

Few other researchers have studied the question, and those who have posed the questions differently and surveyed other age groups. For example, one study found that teenagers whose first sexual encounter was casual rather than romantic were more likely to report psychological distress. Another found that college women who engaged in casual sex were more likely than their male counterparts to report depressive symptoms.

But Eisenberg said her study is the first to include a wide cross-section of young adults. Two-thirds were white, some were full-time students, some part-time, some in college, some in community or technical schools and some weren't in school at all.

They did find some differences among the groups. Black men, for example, were more likely than white men to describe their last sexual encounter as casual. And twice as many men as women said their last sexual encounter was casual - 29 percent compared to 14 percent.

That difference raises the obvious question: How can there be twice as many men having casual sex as women? The answer, Eisenberg said, most likely lies in cultural norms that make it more acceptable for men to describe their sexual encounters as casual.

"Young women have more of a tendency to characterize it as more special than, perhaps, the man did," she said.