I'm not surprised scientists now think adolescence goes up to 24 – sometimes I wonder if it might stretch further

Apparently adolescence now spans the ages of 10 to 24 rather than merely teenagehood – that’s according, at least, to scientists writing in the Lancet Child and Adolescent Health journal.

On certain days, if you happened to be spying on me, you may argue that they last up to your 40s. Just the other day I was snappy with my mother who kept insisting I should wear a cardi. I didn’t want a cardi, I told her so, but she still went and got me a cardi. I tutted and hissed, “NO. I’m FINE.” Then remembered I am 44 and I’m being grumpy with a woman in her seventies who used to wipe my bottom.

But it can be hard not to slip back into being a sulky adolescent when your mother is fussing about you.

I already irritate my child by acting like he’s Scot of the Antarctic leaving his tent without a coat rather than a robust 10-year-old walking 300 yards to his London school in a hoodie.

I can see how 10 is the start of adolescence. My boy is learning that the home is a great place to question authority and practice recalcitrance.

“Are you going to brush your teeth?” I snapped recently, as I’d asked for the third time. There was still no urgency on his part to get ready for bed so that Mummy could sit down with a cup of tea and eat the chocolates she has been hiding in a shoe box.

Put out by my tone and not being the sort of boy who would be outright rude, he replied: “I have no idea, I’m not a soothsayer.”

I have no time for wit when I am desperate for peace, quiet and privacy to stuff my face, so I snapped again: “Don’t be such a smartarse.”

I am not proud. Squabbling with your own child is never a good look, but I’m only Mary Poppins during parenting challenges 99 per cent of the time. (I’m also not much better than Pinnochio at lying.)

There was a time when my child would have leapt to his feet at such an obvious sign of his mum about to lose her temper, and done her bidding. But instead, he said calmly said: “Oh dear. Someone needs a nap,” and sauntered off in the opposite direction to the bathroom.

And so it has started. He is entering the phase where he sees his mother merely as the annoying person trying to stop his teeth from rotting or prevent him from catching pneumonia when it’s all totally pointless because he already knows everything anyway.

I can see how the official “adolescent” lifespan has been extended to 24, and I can expect an avalanche of smartarsedness for another 14 years. It does make sense, though, to make allowances for young people’s behaviour beyond their teens.

I’ve always said that after 25, everyone is the same age. Before 25, I can forgive most brattish behaviour but after that, if you throw your toys out of your pram, I’ll throw them back at you.

I have many friends in their early twenties. By “friends”, I mean “babysitters” but regardless, they become friends and I enjoy spending time with them and hearing all their ideas and concerns. I’m at an age now where I find myself saying, “I DO enjoy the company of young people, they give me energy!” then shuffle off to find some custard creams.

I feel maternal and protective of a 21-year-old in the way I don’t with a 26-year-old. Their gait changes: it’s less bouncy and they keep their arms closer to their sides when they run. Most seem much less excited by ice cream.

Of course everyone is different and there are exceptions. My mate Tom Lucy, for example, is a fellow comedian who is 21 and quite clearly “an old head on young shoulders”, as the expression goes. You have to be pretty together to be completely financially independent at 21 – it’s fairly rare these days. People are moving out of home later and going up at their sentences more when they are young? Which makes everything sound like a question? So they don’t sound sure of what they are saying? So I imagine an employer can’t be sure if they want the job or not?

Rather than infantilising young people, acknowledging that adolescence runs on until our twenties will perhaps allow us to give our much-maligned youth a bit of breathing space and understanding. I was prone to a bit of tantrumming well into my twenties. It’s bloody hard navigating your way around adulthood when your brain is still developing and you’re wondering what starsign the person you fancy is.

This latest scientific announcement, however, does not explain my four-year-old daughter’s penchant for slamming doors and eye-rolling. Though perhaps her DNA does.