Generally speaking, when are you too young to have sex?

Inspired by this question (and its ensuing mess)...

This isn’t going to be a typical “Am I too young to have sex?” question. Instead, when looking at the answers to the above-mentioned question, and when thinking of the age of the questioner (if you’re reading this, nothing personal mate, you just inspired me to think that’s all), I found myself wondering why some of the answers didn’t mention a thing about the questioner’s age while others were having their misgivings about what he was planning to do at his age.

I know that there is no one set rule on this, no ‘Thou Shalt Not Copulate Below the Age of 12’ or whatnot, because it all depends on the individual and his/her circumstances. But because of our upbringing and because we’re the people we are, I’m very sure that we’ll all have a certain reaction to a youngster saying that he/she wants to lose his virginity, be it positive or negative (or even apathetic).

But what do you think? Do you think that there is a general age people should be above before they even try sex? I, for one, would be extremely uncomfortable about a 14–15 year old wanting sex. And if it were in my power, I’d do my utmost best to forbid a 12 year old from having sex, whatever their genitals tell them. I’ll only start being more comfortable once they hit 16, because I assume that they’ve reached a certain maturity level (although yes, I know that this is a gross generalisation, there are also many exceptions to the rule [or more aptly, guideline]).