Listen, >>1, before I answer you I'm going to hijack the thread and say something related:

I hate it when people say doing drugs is a "victimless crime." Maybe if they just lived in isolation in a little glass box it would be. But other folks have to deal with people who are drunk and high, and often drug users will commit crimes when high and not thinking straight, and if not that, they'll get addicted and lose their jobs and become a drain on the community. All of society is a victim in these cases. So I'll take none of that "victimless crime" nonsense.

Certainly, it's better if you let your children think for themselves rather than say "This is right and this is wrong, end of story." Which they'll ignore anyway, in the teenage stages. But I think actually supplying a drug isn't necessary and is probably a bad idea.