What is it about sex education that causes some otherwise rational adults to behave irrationally?

When it comes to other topics -- smoking, drinking, drug abuse -- we don't hesitate to give our children the benefit of an unambiguous "no." We tell them flat out that they shouldn't do it. If anyone said, "But kids are going to drink any way, so let's show them how they can minimize the effects of a hangover," most parents would suggest that that person have his head examined.

Yet who can deny that the same logic (or lack thereof) lies behind the push for "comprehensive" sex ed? In the name of "safety," we've allowed a river of pornography to flow through our schools for the last couple of decades. "Condom races," in which teams of teens compete to see who can unroll a condom onto a cucumber the fastest, are only the tip of the truth-is-relative iceberg here, folks.

Well, I'm not the only parent (thank God) who thinks this in unacceptable. A recent Zogby poll shows that 91 percent of parents want their children to receive a clear-cut abstinence message. And many school districts nationwide have gotten the message and ditched their "safe-sex" and "abstinence-plus" programs for true abstinence ones.

Now we're hearing a growing chorus of liberal voices claiming the abstinence-only programs that parents say they want their children to receive are misleading, naïve, ineffective and damaging. These programs, critics say, leave innocent teens to face sexually transmitted diseases (STDs), pregnancy or worse without proper knowledge of how to use the almighty condom.

Those voices have made two media splashes lately. One is a hysterical column by Frank Rich in The New York Times that makes it sounds as if backwoods red-staters want to make sex illegal. The other is a report published on House Government Reform Committee letterhead and signed by Rep. Henry Waxman, a Democrat whose district includes Hollywood. According to the Waxman report, abstinence programs are subjecting students to "false and misleading information" about sex.

Well, do the programs work? The Waxman report and the Rich column both claim that abstinence programs haven't been shown to be effective in preventing teen pregnancy or reducing STDs.

But Robert Rector and Melissa Pardue, two scholars at The Heritage Foundation who research these policy areas thoroughly, say 10 scientific evaluations (four of them peer-reviewed) have found abstinence programs effective both at reducing teen pregnancy and at reducing sexually transmitted diseases.

And abstinence programs do even more, Rector notes. They "also can provide the foundation for personal responsibility and enduring marital commitment," he writes in one Heritage Foundation report. "Therefore, they are vitally important to efforts aimed at reducing out-of-wedlock childbearing among young adult women, improving child well-being, and increasing adult happiness over the long term."

Rich also ripped into virginity pledges -- in which students pledge to abstain at least through high school -- calling them ineffective and downright dangerous. But another Heritage report that relies on data from the federally funded National Longitudinal Study of Adolescent Health shows how wrong he is.

"Adolescents who take a virginity pledge have substantially lower levels of sexual activity and better life outcomes when compared with simi­lar adolescents who do not make such a pledge," the report says. "In addition, making a virginity pledge is not associated with any long-term negative out­comes. For example, teen pledgers who do become sexually active are not less likely to use contraception."

Plus, as my friends at Project Reality point out, if condoms were effective at reducing STDs, then, as condom use goes up, STDs should go down. But they've grown right along with condom use.

Seriously, who can deny the dangers of sex for teens? We know that the rates of depression and suicide are higher among teens who are sexually active. We know sexually active kids are more likely to drink, smoke and use drugs. And we know -- as parents, educators and members of the community -- that kids strive to meet the expectations we set for them.

If we subject our children to programs that say, in essence, "We know you're going to have sex," we shouldn't be surprised when they do. If we tell them we expect them to abstain, on the other hand, many of them (not all, but let's be reasonable) will do just that.

We owe them the truth. And the "safe-sex" message is a lie.

Rebecca Hagelin is a vice president of the Heritage Foundation.