Any time now we can expect another one of those real-life "Home Alone" scandals featuring some selfish single mother flying off to Spain and leaving her two neglected kids to fend for themselves back in the council flat.
"Jamie – were you frightened when you realised Mummy wasn't there to tuck you up in bed at night?"
"Not really. I'm a 27-year-old finance clerk. I think I can manage."
"And you're able to cook your own dinners and everything?"
"What? You mean she hasn't left me any prepared meals?" screams the bearded Jamie, as he bursts into tears and is taken into care by social services.
Our children are remaining dependent upon us long after they cease to be children. This is the conclusion of a new book by two academics from Oregon State University (or the project may have been completed for them by their parents, it's not completely clear). Not Quite Adults argues that it often makes economic sense for twentysomethings to keep living with Mum and Dad, and that extended families have worked like this in many societies down the centuries.
But I have to say I fear for the sanity of the entire family. It's bad enough going back to your parents' at Christmas, but who wants an entire decade of having the telly too loud and the heating too hot and not knowing quite where to start when they ask why the blacks are reading our news.
An Italian minister has even suggested that there should be a law to force Italy's mollycoddled bamboccioni to leave home at 18. That's the sort of age that a girl should be making her own way in the world, by say, getting a job in Silvio Berlusconi's cabinet. Here in Britain, junior positions have been re-graded as "internships" where applicants are chosen not according to talent or aptitude, but by the fact they are prepared to take "experience" in lieu of a salary. So all the really interesting opportunities are being filled by fresh-faced public schoolboys working for nothing. It certainly explains how George Osborne got to be Chancellor.
All across the Western world, the combination of housing costs, pitiful starting salaries and student debt, combined with the overbearing nature of modern parenting, is creating a generation whose transformation into true adulthood is delayed by up to a decade. This is a far cry from the romantic J M Barrie notion of the boy that never grew up. A modern-day Peter Pan wouldn't be for ever playing in the forest; he'd be stuck in his bedroom, leaving slightly creepy comments on Wendy's Facebook page, while downstairs the grown-ups were worrying if the balding Peter had followed up any of those job opportunities they suggested.
A symbolic milestone used to occur when young adults went off to university to learn about philosophy, sociology and overdraft charges. But the cost of fees is forcing students to opt for universities in their home towns, to save the cost of food and lodging. This misses half the point of going off to college, which is to learn to take responsibility for your own life, managing your own finances and setting your own 11.30am alarm call. You have to learn to be considerate to that one hard worker in your student house, who moans about the drunken noise you make at three in the morning. But you don't want it to be your Mum. And you certainly don't want Dad coming down in his pyjamas to join in the late-night discussion on the meaning of life. "Ooh I tell you who I think is very good – that Lady Gagaga. Though I'm not sure she is a genuine member of the House of Lords. Are you counting those magic mushrooms as one of your five a day?"
The family home used to be a strict and repressive place, according to an in-depth study of 1960s Alan Bates movies. It was somewhere you couldn't wait to escape from. Now the atmosphere is more laid back and parents and teenagers are more involved in one another's lives. The kids are listening to the Beatles on vinyl while Dad downloads Radiohead on to his iPod. And parents can postpone the notion that we might be growing old as long as our kids are still at home and we're all wearing roughly the same jeans/T-shirt combo.
Perhaps it is changing attitudes to sex that has made living with your parents tolerable. Once upon a time, unmarried adults couldn't wait to get a place of their own, so they weren't forced to have it off round the back of Roxy dancehall. Now they are bringing their girlfriends or boyfriends home and Mummy makes up the double bed and probably puts a condom on the bedside table as well. "Don't forget to do your foreplay darling!" Mum will shout through the wall encouragingly.
But young adults need to learn to be independent – to deal with gas bills and piles of unwashed clothes and empty fridges. That RSPB Big Garden Birdwatch isn't going to do itself, you know.
And we need to let them go, and then turn around and reintroduce ourselves to that person we married all those years ago. Having our kids live with us long into their twenties is a betrayal of everything that the baby-boomer generation had hoped and planned for. We were supposed to be the ones who'd be an enormous burden to them. But it seems that only after they turn 30 will they finally move out and settle down, giving them about 18 months' genuine independence. And then semi-senile and pensionless, we'll say, "I can't cope, dear. Would it be all right if I came and lived with you?"
John O'Farrell's most recent book is 'An Utterly Exasperated History of Modern Britain', published by Black SwanReuse content