I doubt anyone was shocked to learn almost a third of under 16s have had sex, although I was mildly surprised this figure accounts for more boys than girls - 30% compared to 26%.

When I was 15, in what now seems such a far-off time it might as well be the Edwardian age, girls were the more mature, physically and emotionally. Boys meanwhile were embarrassed even to be seen holding hands with a girl.

That was alright, though, because the 15-year-olds in my class who said they were sleeping with their boyfriends wouldn't have been seen dead with their peers. Older men - 18 and 19-year-olds - were the epitome of glamour, though probably less help with their homework.

The suggestion by Professor John Ashton, president of the Faculty of Public Health, that the age of sexual consent could reasonably be lowered to 15 has predictably set the hornet's nest buzzing. To combat the rise of sexually transmitted diseases and the worst rate of teenage pregnancy in Europe, he wants youngsters to have easy access to the medical services they require once sexually active, without fear of being reported for underage sex.

Otherwise level-headed, Prof Ashton says setting the limit at 15 will "draw a line in the sand" and discourage anyone from embarking on sex before then. This seems somewhat naive. Those of a mind to start earlier won't be put off by a lower age of consent - if anything, the reverse. It's like raising the speed on motorways: some will always take a legal limit as a green light to transgress.

Perhaps for this reason, but more likely because of innate caution, Prof Ashton's suggestion has been rejected by both David Cameron and Nick Clegg. It doesn't need a clairvoyant to see that the idea has been stillborn.

And yet, whatever one's opinion, this subject is crying out for debate. Increasing pressure on teenagers to be sexually active, not to mention the consequences of disease and pregnancy, seem to be part of a spiralling culture of sexualisation of the pre- and newly pubescent. Underage sex has been a fact of life since the law books were first written. What is new, however, is the insidious, cynical, ceaseless targeting and exploitation of youth by those intent on selling sex, and ideas of sex, that are deeply damaging at that - and perhaps any - age.

Of course, the thought of those just out of childhood having sex has always been difficult to discuss, particularly for parents. Sadly, if understandably, when it comes to this most private aspect of life, only the most enlightened or most severely interrogated child will reveal all to their mum or dad. Those who claim there is nothing their offspring will not discuss with them are living on Planet Denial.

For a start, I suspect many would be appalled at the pornographic education their children have received, long before they are 15. Indeed, the fact 266 girls under the age of 14 had genital cosmetic surgery on the NHS in the last five years is alarming on every level. Not only does it suggest standards set by the porn industry are now in the nation's bloodstream but, worse, that children are comparing their bodies against the ideals they set.

To bolster his argument, Prof Ashton points to countries such as France or Italy where the age of consent is lower -15 and 14 respectively. In Spain, it is 13. Comparisons are meaningless, though, without an understanding of the societies in which these laws exist. More persuasive, to my mind, is the professor's attitude towards the young people he is talking about. Unlike many moralisers he treats them with respect. Medical pragmatism is the root of his cause, but he tempers this with an awareness that for some 15-year-olds, having sex with someone of a similar age is not a disaster, but a natural part of growing up. It only becomes cause for serious concern when ignorance, embarrassment or fear result in far-reaching medical or psychological consequences.

Without knowing a great deal more, I wouldn't want to be the person who signs a decree lowering the age. Even so, teenagers and their parents clearly deserve a debate that is conducted not with moral outrage or hysteria about paedophiles, but with tolerance and understanding. That, surely, is the adult thing to do.