You can distinguish between facts and values. For instance, it is a fact that a very large majority of humans are either clearly male or clearly female, and the adults are heterosexual. It is also a fact that there is a very small minority whose physiques have both male and female characteristics, another very small minority who are physically one sex and psychologically the other, and a somewhat larger minority who are homosexual or bisexual. There is another small minority of adults who have no sexual orientation; they are simply not interested in sex.

All of these facts can be taught. The differences between male and female physiques can be taught. The mechanics of sexual interactions can be taught, even those interactions that some people consider "sinful" or "perverted", without introducing any opinions about the rightness or wrongness of particular interactions. In short, teach facts at school; teach values at home, or church.