Or rather, for their parents... while sex information etc seems to have a home in the wikipedia, parents might not be thrilled at the idea of Junior reading up on anal penetration, cock rings, and other 'adult' concepts. I know I wouldn't if it was my kids... some things are just not for juvenile eyes, if only because too much information leads to very awkward questions.
The front page should have a note on it in the introduction, saying something like 'While the wikipedia does not condone obscenity, articles may contain adult concepts and language unsuitable for children. Please supervise your children's access.' or whatever...
I strongly object against this. This implies that the concept of obscenity is generally shared, which it isn't. If you get your obscenity warning label, I want my "religious content" warning label. And someone else may want a warning label that Wikipedia may be offensive to people having suffered from certain traumas. And maybe the creationists and anti-abortionists want one, too.
Wikipedia is an *encyclopedia*. That implies certain things. If you don't want your children to learn, don't allow them to read -- that is your right as a parent. But not everyone wants children to be kept ignorant of sexual matters (or the ideas that lead to such indoctrination to be perpetuated uncritically).
Regards,
Erik