Yes, we do need to change the age of consent. To 35. Only then are people ready to have sex

The first pleasure of bodily love isn’t penetration - it's disobedience

I’m out of the country for three weeks and already there’s talk of lowering the age of consent. This can’t be coincidence. I must assume that knowing my views on the subject and hoping I’d be gone for even longer, Professor John Ashton, president of the Faculty of Public Health, quickly ups and proposes to David Cameron that we allow 15-year-olds to have sex. Not much of a concession given that most 15-year-olds have already had too much, but these things are symbolic, which is why, no matter what is actually going on out there, I’d move in the opposite direction to Professor Ashton and raise the age of consent to 35. Let the 15-year-olds in question know what we think, no matter that they’ll ignore it.

I am a believer in making unrealistic demands of the young. It’s important they confront a challenge. I recall envying schoolfriends whose parents let them sleep with their girlfriends in the spare room – though not as much as I envied them for having girlfriends in the first place – but later noted that these were the boys who went to ruin soonest. No moral compass. No exemplary prohibition.

You might think you want your parents to be your pals, your partners in sexual mischief, but you don’t. You want them to be forbidding Noboddadies, silent and invisible, fathers and mothers of jealousy and inhibition, whose commandments you will of course break, but in the breaking of which you come to understand the first pleasure of sex which isn’t penetration but disobedience. Here is what we lose when we remove the concept of wrong from sex: secrecy, connivance, terror and, above all, argument. There is more than one attitude to take to sex – and you’re a goner as a moral being if you aren’t taught that early.

I detect demurrals from the Health & Efficiency brigade. Let sex flower naturally, they say. But whoever thinks sex is natural and therefore to be unambiguously encouraged has never seen it, never done it, never thought about it, and never seriously weighed its consequences. I’m not proposing that we din Shakespeare’s testy description of lust in action as an “expense of spirit in a waste of shame” into our children the moment the subject’s raised. But I’m grateful to my parents for warning me that I was likely to experience as much disappointment as delight, for cautioning me against impatience, for suggesting there were other things I might do – table tennis was one of them – and for not letting the girlfriends I didn’t have sleep with me in the spare room we didn’t have either.

We do those we are charged with bringing up no service by pretending to be no older or wiser than they are. To do so only deprives them of precept and example. And don’t be fooled by their apparent scorn for such things. They might not know what the words mean but they miss what they denote when it’s not on offer. And part of that is a sympathetic but well-reasoned rebuttal of pornography. We can’t stop them looking. We used to look ourselves. Many of us are no doubt looking still. How could it be otherwise?

Pornography became inevitable for Homo sapiens the moment he turned sapiens. We ate of the tree of knowledge and immediately wanted to take dirty photographs. But you can look and know you shouldn’t. You can look and gauge the damage that looking does. D H Lawrence’s denunciations of pornography and “the masturbation self-enclosure” helped me when I was young – not to give it up but at least to be in a debate with myself about the subject. And that’s the parental role: to be the other side of the argument, to make the case for harm in an age where the very idea of harm in the matter of sexuality (a word that is itself part of the problem) has grown dangerously unfashionable.

Thirty-five, then, kids, is when we think you are ready to start. This will come as a shock to you because you believe 35 is when you’re meant to finish. “Gross!” you call the thought of people that age perspiring naked in one another’s arms. “Ugh!” you cry, putting your bitten fingers down your baby throats. But all that proves is that you too are moralists who lack the words you need to moralise with. Allow anything about sex to disgust or dismay you and you are admitting that the procreative impulse is susceptible to judgement.

We have let you get away with judging us for too long. Time now for the rightful order to be restored. We teach you. And the single thing you can teach us in return is that teaching is what you hunger for: the gift of our experience. Tell your parents that. Tell them you’ve got plenty of friends, thank you all the same – remind them that you perform fellatio or similar on most of them – but what you’re short of is intelligent authority.

And 35 is not as arbitrary as you think. This might surprise you but in the main people get better at sex as time goes by, not worse. Sure, you lose a little in the way of athleticism, but what you forgo in elasticity of body you gain in flexibility of mind. You notice more. You discover that the slow accrual of mutual fondness adds savour to sensuality. And with luck you will by that time have evolved a sense of the ridiculous, which can be a nuisance during sex but is wonderfully consoling after it.

In the meantime, accept that most of what you think and do you shouldn’t. If you don’t know that sex is trouble, a pleasure and a plague, no sooner done than regretted, and no sooner regretted than missed – in short, perplexing and unfathomable – you aren’t ready for it.