Surveys must be taken cautiously, especially when attached to a book launch. Jacqueline Wilson, a teen-read bestseller, says that modern children grow up too fast: “Parents are well-meaning but they need to set boundaries.” She speaks out for simple family pleasures such as picnics, and her publisher releases an ICM poll on attitudes to childhood.

Parts of it are pointless: the figure of 71 per cent of parents giving under-18s alcohol at home makes no distinction between a well-governed child allowed a glass of wine and a poor brat getting senseless on alcopops while its parents shoot up.

It does seem odd that more than half of under-16s are allowed out after 11pm, given that two-thirds of parents then claim to be worried about the company they are keeping: perhaps they just enjoy worrying. But the key finding is that 55 per cent “think childhood is over at the age of 11”.

Now that is interesting, and worryingly believable. Eleven is not very old: five years must elapse before the child can legally make love or earn a living. Even at 14 the brain is physiologically changing, experience of life is minimal, sexuality confused, emotions chaotic. Even if puberty strikes early, these are still children.

But it suits adults for them not to be. Despite the chattering-class perception that we overprotect, secondary school at 11 all too often heralds a kind of parental abdication. The weaselly expression “young adults” kicks in. When my eldest first went to “big school” he found the jostling lunch queue so frightening that he stopped going in at all, and hid hungrily in the library. Nobody noticed. When we found out after some weeks and remonstrated with the idiot head of year, she replied gaily: “Oh, it's not a primary school, we don't police their day, young adults make choices.”

His next school took a saner view, but looking around I recognised the “young adult” mindset everywhere. Once primary school cosiness is over, the child is seen as having stepped into a wider world and joined a tribe of peers with new customs. Adults, nervous and preoccupied, may take the opportunity to step back farther than they should.

There are plenty of reasons. Parents could be holding down two jobs or more, because of the absurd price of homes and government's droolingly incompetent failure to plan for a rocketing immigrant population and the fallout from council house sales.

Family life and family meals suffer under heavy work pressures: how could they not? Besides, adults are tired and it takes energy and resolution to say no to beloved teenagers. Simpler to give them their “choices” as “young adults” and disguise emotional neglect as respect. A disastrous misunderstanding of the Children Act has made adults frightened of exerting authority, and even professionals talk nonsense. One would-be adopter, asked by the inspecting social worker if she would ration TV, said yes, an hour a day. Wrong answer. She was sternly told that this would violate the child's “human right” to “participate fully in the culture”.

Even when financial and time pressures are light, cultural values militate against looking after children properly. It was interesting on Mothering Sunday to follow, parallel to the usual soppy blether, a whine about how tough it is to be a mother and how it drains your “selfhood”. It is as if we wanted to be the children ourselves, petted and admired and given playtime and toys. Men also are encouraged to embrace a permanent adolescence of gadgets and treats. Children get in the way of this, especially when they stop being sweet and cuddly and believing everything you say.

Surprisingly often they become resented: I have heard a mother say, vindictively, of her 12-year-old: “That kid never brought me no luck.”

Further up the social scale parents may be less frank, and just push the awkward-aged child into expensive activities and tutorings outside the house rather than ignoring it. But the same feeling of petulant, disappointed unwillingness to engage with a child's troublesome reality is sometimes discernible. Oh yes it is.

So into the vacuum comes a rush of alternative parents, greedy for the children's money: television and internet, celebrities, showbiz dreams, gadgets, fashionable must-haves, social websites, computer-game illusions. Where there is no money, out on the meaner streets, gangs become surrogate families offering leadership and protection and rules to live by. Not good rules, not at all - but they fill the gap.

There is an opposing force at work too, and that is the desire to suck up to youth and annex its more desirable qualities - energy, smooth skin, skinny thighs, big-eyed winsomeness, freedom. Stars dress like teenagers, grown men write drivel about pop, queenly Nigella Lawson goes on Desert Island Discs to express hip-hop kinship with Dr Dre of Niggaz With Attitude.

If I really wanted to upset you I would call this phenomenon cultural paedophilia. The late Alan Coren summed it up beautifully when he said that in his youth in the Fifties he sought to attract girls by dressing in broad-shouldered George Raft suits and trying to look 40 - but no sooner had he succeeded, than in the blink of an eye the Sixties arrived and the sexual norm of male desirability became “a skinny kid in a tattered Donald Duck T-shirt”.

Very perceptive. There you go. Half the time we admire late childhood as cool and sexy, the other half we ignore it as awkward and spotty. Either way, we find it easy to treat it as a different but equal “culture”. And it isn't. It's childhood. Someone has to be the grown-up round here, and I'm afraid it's us.

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