I realize this is a very thorny topic, but it really is of the utmost importance, and not talking about it only serves to make matters worse. As far as cultural attitudes go - which influence individual opinions - what we believe influences what we teach new generations. And if those beliefs are toxic, then we need to be extra careful not to let them influence what we teach our children. Now on the topic of sexuality, I believe that many of our cultural attitudes, and therefore many people's individual opinions, are toxic. And the best way to cut them out (seeing as people are very stubborn about changing their longheld beliefs and traditions, even when they want to) is to prevent new generations from picking them up in the first place.
In other words, we have to teach our children right. But on the topic of sexuality, we're so paranoid about children these days, that we'd rather teach them nothing at all, or wait until long after it's too late. But they're learning, nonetheless. They're picking things up from their environment, from the media, and from their peers, and they're picking up cues from their parents' attitudes toward sex as well, even if unintentionally. As a parent, you can either be an active part of that learning process, or you can step aside and let the chips fall where they may (which I would not recommend).
I mean, we can't teach children sex-negative values and then expect them to instantly adopt sex-positive values once they're "old enough". It's an unbroken continuum of knowledge. Children eventually become adults, and the things they were taught as children form a strong foundation for what they believe as adults. I just don't believe that a healthy attitude toward sex is something that has to be recovered through therapy (of one form or another) from the ashes of a sex-negative upbringing. We ought to teach people to view sex from a healthy perspective the first time around.
I know, nobody wants their children 'getting ideas' about sex when they're still so young. There is such a thing as age-appropriateness. But it ought to be guided more by the child's curiosity and development than its parents' fears. Properly educating children about sex does NOT mean oversexualizing them, but it doesn't mean DE-sexualizing them, either. Nor does it mean "protecting" them by hiding sex from them. If they're curious, sate their curiosity. If they're uninterested, don't bug them with it, but make sure you're available when they do begin to have questions.
And above all, be open and honest and don't fall prey to the trap of thinking that certain subjects aren't "appropriate" for children. You can tell your kids that having sex isn't appropriate until a certain age, but you can't tell them that knowing about sex isn't appropriate. Withholding knowledge when the curiosity exists is extremely dangerous. They will seek out the knowledge elsewhere, and the information they get can be harmful to them (as well as the lack of knowledge), and they can get it from sources who are not invested in their best interests.
None of this suggests engaging in any kind of inappropriate behavior with children - learning boundaries is an extremely important part of a proper education. It's about knowledge, and prevention. As I said, kids are getting information about sex from every direction, consciously and subconsciously, beyond our control. Much of it is bad. So instead of plugging our ears, why not try countering the bad with some good? By waiting too long to have 'the talk' - which should be ongoing and not a single, isolated event - we've given up on teaching our kids about sex, because they've already picked up the sex-negative, shame-promoting values that permeate society. And that's not healthy.
I see really inspiring pioneers on the subject of sex and society, going on and on about sex-positive this and sex-positive that - and that's great. But then when it comes to the topic of children, it's always, "let's recoil in fear," because it's such a huge taboo, and these people have reputations to protect. But this is not only dangerous for the children, it actually undermines our whole attempt at curing our poisonous attitudes toward sex. Because, what we teach our children is what the next generation of adults is going to believe. And when I see the way we treat children with regard to the topic of sexuality, there is no wonder in my mind that there is so much sexual dysfunction in the adult world.
And it's got to stop. But we're screwed until we begin to realize that.