Sex education started about a century ago, when fears of venereal disease seized the American middle class. Newspapers carried lurid stories of well-to-do men who acquired VD from prostitutes, then infected their wives. So physicians and educators created curricula to warn children about these dangers and discourage any sex outside marriage.

That remained the central theme until the 1960s and 1970s, when liberal educators developed a new curriculum based on student choices rather than teacher directives. Known today as "comprehensive" sex education, this approach echoes the following message: Sex may be pleasurable but can be dangerous; so if you decide to have sex, minimize the dangers. That is, use protection.

The protection part became even more urgent in the age of HIV/AIDS. To liberals, of course, the AIDS crisis simply reinforced the need for clear information about contraception.

But conservatives drew the opposite conclusion. To keep children safe from pregnancy and disease, we must transmit a firm and simple message: no sex before marriage. And so abstinence-only education was born.

Tucked into the welfare-reform bill of 1996, it got a big boost from the Republican-dominated Congress in 2001. And it still
draws $176 million in federal money, even though – as we now know – it doesn't make children more likely to abstain from sex.

First of all, we don't know that it works any better than abstinence education does. Teens are using contraceptives more regularly than in the past, but they're abstaining more from sex, too!

Second, the liberal demand for comprehensive sex education betrays a rather illiberal sentiment towards conscientious objectors. In matters of sex, like war, there are some Americans who think there's only one good choice to make. Why should their children be subjected to a curriculum that violates their deepest beliefs?

What do we know? Sexuality is a profound and deeply contested part of the human experience. People around the world differ radically about its purpose, meaning, and implications.

Instead of trying to alter sexual behavior, the course would examine the different ways that human beings – across space and time – have conceived of sex itself. It would draw upon texts from history, literature, anthropology, and religion. And it would expose children to the enormous range of views on sex, instead of imposing a single view upon them.

Right now, both sides of the sex-education debate still insist that education can change sexual activity. And as best we can tell, they're both wrong. Maybe the new demands for science-based curricula will remind all of us about the complexities, ambiguities, and diversity of sexuality itself. Come to think of it, that would be a great focus for a course.