The thing is, in raising kids, you can NOT watch them 100% if the time if you want to let them learn to be a grown up. Its not healthy for them or the parents. At 12, yeah, I had freedom to walk around to friends houses, hang out after school at houses where parent were still at work, etc. I never even thought of having sex, was still working up to my first kiss lol BUT I had friends that were a bit more advanced.
The important part is NOT watching them all the time, forbidding things, etc...its teaching them reality. Teaching real sex ed, explaining feelings that are going to come up, what happens, why it happens AND imo its very important to teach safe outlets for those feelings.