Ah, the old "well they're gonna do it anyways" approach. Gee, I have no idea why kids are so out of control these days. :roll:
On the contrary, it's mostly the children of highly authoritarian anti-reality parents who wind up with these problems. The ones who think abstinence-only should still be pushed despite its complete failure, the ones who think threatening people with years or decades in prison is a sane solution to college kids smoking pot, the ones who think of other people a bit like dogs; they're to be trained, not talked to.
The ones who grew up like that are the ones having children as children, doing drugs, etc, for reasons explained below.
Sorry, I don't understand what you're saying. When does the words of the parents outrank what the 12 year old wants? How about sex? Drugs? ...
The most successful method of keeping children from doing drugs or having sex too young is education and making sure they actually understand the risks, not authoritarianism.
This is the basic principle that underlies fact-based sex ed, which is extremely successful in both delaying sexual debut until the late teens and beyond, and bringing down teen pregnancy and STD rates dramatically.
Teenagers are naturally paranoid. Contrary to popular belief, psychological research shows that they tend to over-estimate the risks of what they're doing. But they can only do that if they actually understand the risks. Understanding is why fact-based sex ed works, and authoritarian abstinence-only does not.
12-year-olds don't think like 4-year-olds. They have at least basic cognitive faculties which they will use to question whether your authority is legitimate, and they respond better to conversation than they do to dog training techniques.
Even the most authoritarian parents cannot completely control their children once they start getting towards their teens just by commanding them. Believe me, I know; I was partying with those people's kids. They jumped out of second-floor windows, risked having their entire room emptied to a barren shell, and I suspect possibly an ass beating, to come party with us.
Your children will be exposed to the real world, and if you want to stop them from taking on too much too soon, have a little consideration for their developing minds. They're not dogs. And more importantly, as Summerwind said, establishing yourself as a safe and reasonable person to talk to about the issues they face can save them from a lot of harm.