It's worth noting that America is the only developed country where abstinence-only education exists in public schools. In Papua, New Guinea, the Trobrianders give children nearly unfettered access to each other at very young ages: 6-8 years of age for girls and 10-12 years of age for boys. The Trobrianders see nothing shameful about consensual sex, and feel that it's a vital part of living a healthy life. One can see the value in saying that behavior that's normal and natural for an adult shouldn't be shamed in children.
Exclusively heteronormative sex education is also something we can do without, although it remains the norm in much of the country. California has recently proposed legislation that would include HIV prevention education, and to include LGBT information as part of the standard curriculum. California Assembly Bill 329, as it's called, was approved by the state assembly and is currently en route to the state senate. Parents still have the option of removing their kids from sex ed class. That's better than the previous opt-in option that required parental approval before a student could attend a sex education class at all.
The landscape of sexual education in American public schools is filled with rocky terrain. Only 35 states require that any sex education be taught at all. Of those that do require it, a few allow for only abstinence-only education while others insist on a more inclusive and realistic curriculum. With no national standard in place, it often falls to specific districts or even individual teachers to determine what's best for their students at a given time.
I think most teachers can be trusted to know what their students are ready for; the impact that a single teacher can have on a student's perceptions about sex is enormous. Yet, being taught sex negative things at an early age can have lasting repercussions that lead to devastating consequences. Kidnap victim Elizabeth Smart famously explained that the sex-negative information she received in an abstinence-only class made her reticent to try to escape her attacker. She had been told that non-virginal girls were akin to a "used piece of bubblegum" leading her to presume that she had lost her value as a human being because she had been kidnapped and raped.
How do we go about getting comprehensive, evidence-based sex education in all 50 states? I'm really not sure. I do think it will take effort from teachers, administrators and parents working together. Hopefully, this happens without input from groups who seek to deny students the information they need and deserve. Some kids are going to have sex no matter what they're taught. The least we can do is to provide information that lets them explore their sexuality safely and with their dignity intact.