Are you trying to suggest that any 12/13 yo is going to start experimenting with just any other 12/13 yo? That's ridiculous. We're not talking about friends, we're talking about boyfriend/girlfriends. And if you know your 12 yo is lusting after another 12 yo in your neighborhood perhaps it's time to start acting like a parent.
That said, like I said, most 12/13 yo's I know are not just hanging around in the neighborhood anymore. They've grown out of that. They have lots of homework to do. They are seriously involved in extracurriculars. They have yet to hit the "hang out and relax and party scene" that is more typical of high schoolers. My own dd sees her friends in school, at each other's houses if they are working on a project (with parent, who I know, present) and occasionally at sleep overs (again with parents, who I know, present). The rest of the time I know exactly where she is. So where exactly is all this experimenting supposed to take place
This notion that a parent doesn't have any control over a very young teen is absurd.