30 is the new 20. Any ‘Keep Calm’ themed birthday card in Clintons can tell you that. As can Jay-Z in ’30-something’ whose evidence is largely centred on the fact that he’s ‘so hot still’ with a ‘better broad, better au-to-mo-bile’.

But while it’s nice for 43-year-old Jay-Z that he is still rapping away, and it’s nice that Meryl Streep gets to do mid-air splits in her Mamma Mia dungarees at nearly 60, and that people are calling themselves ‘quintastic’ at 50 rather than old, not everyone is a winner in this cheat we’ve pulled on Time.  This way of thinking might be giving everyone over 30 cakes made from rainbows and botox, but no gift to twenty-somethings. In fact, we might be being robbed.

One woman who has been calling for an investigation into this theft is Dr Meg Jay, a clinical psychologist who recently gave a TED talk about her twenty-something patients who are wasting their most important developmental decade. She also wrote a subtly-titled piece on the Huffington Post ‘9 Ways Twentysomethings Screw Up Their Lives’.

I watched the TED talk to see whether she had any more helpful points than the standard don’t -spend-your-twenties-in-your-parents’-house-crying-in-your-childhood-bedroom. I was ready for it to be very American, and for Jay to tell me I was important because I was the future.

There were some strange generalisations. I’m not clear why she summed up one of her first clients, Alex, by saying that she was came into her office wearing a ‘big slouchy top’ and who ‘kicked off her flats’ – apparently twentysomethings with their shit together have to wear fitted clothes and heels (a shame for this 21 year old currently wearing fake Toms which look like they’ve been through a blender).  She also cites fertility as a reason for owning our twenties a bit too often – but that might be my own distaste for the idea that I have any eggs in me which I didn’t eat at brunch.

Nevertheless, as much as I want Jay to be wrong – she isn’t.

She is hacked off with the people who are stealing our twenties, arguing that our culture has trivialised the most important decade of our lives into journo-coinages like ‘twixters’ and ‘kidults’. She isn’t a fan of this new ‘adultescence’ which have painted us as people with nothing but time. Because that is what we will have : nothing but time, and that is pretty dangerously near nothing.

This doesn’t mean that we need to jump straight out of sub-fusc and into wedding dresses, or that we need a five-year-plan (which always sounds a bit Soviet) tapped out in the notes on our phone. But it means that our twenties aren’t borrowed time that we have nicked from somewhere else – they are ours and we could do with owning them rather than being funemployed and watching Disney movies in our pants.

A good quote Jay pulls out is from Leonard Berstein, who said that “to achieve great things you need a plan and not quite enough time.” TED trolls (who knew there was such a thing?) have snidely got back at Jay by pointing out that Leonard Berstein didn’t get married until he was in his thirties. And also that, as this marriage was to a woman even though he was gay, he wasn’t so great at getting on with his life.  But we can still do as the man said, not as he did.

Jay quotes Berstein, and then asks: “So what do you think happens when you pat a 20-something on the head and say you have ten extra years to start your life? Nothing happens. You have robbed that person of his urgency and ambition and absolutely nothing happens.”

We all know that Jesus was dead at 33, that the 27 club are called that for a reason and that Mark Zuckerberg launched Facebook at same age that most of us were crying about having two essays a week. But, American and sickening as it sounds, Jay isn’t talking about matching up to anyone else but ourselves.

It doesn’t matter if owning your twenties means pouring money on your head and dancing its cascade in the City, or disappearing into Asia and filling Facebook with pictures of you in baggy trousers, or writing the awful fiction you always had in you. It just matters that these aren’t called years ‘out’ on some weird, decade-long hiatus before life starts – it just matters that we see them as real years, and know that they are some of our best.