Letting your kids/future kids have sex?

Hope
I'm just curious on what people think about allowing their kids to have sex.
Whenever I have kids I am going to always give them the decision to do it or not. But the only catch is they have to be honest with me. I want them to feel like they can tell me that sort of thing. I want to educate them and get birth control for my daughter if she wants to have sex.
:)