It was reported this week that people age at vastly different rates. A study of nearly 1,000 38-year-olds, which considered 18 physiological markers, found that some were much older or younger than their biological age. But what about our psychological experience of age? Do you feel the age you are? Or will you always be a teenager at heart?

Michele Hanson: I still want to ban the bomb

Here I am, 72, feeling two different ages at once. Younger and older. There are few advantages to this position. My body and mind have separated. The body has zoomed ahead into old age and feels about 99, with finely wrinkled old-lady skin, a general spattering of huge, unsightly moles, pancake face, stoopy posture, and more crawling about slowly than sprinting. But the mind has been left behind, and not in a particularly positive way.

It doesn’t seem to have matured properly. I have never become a proper grown-up. I’ve tried to. I can dress like one, and sometimes speak like one. I think I can fool people for a bit, but I suspect most of them have guessed the truth – that I’m an imposter. Because I’m really 17. I don’t do the washing up promptly, I have tatty animal posters stuck on the wall, and I’m waiting for the revolution. I still want to ban the bomb and think socialism is lovely and the only way forward. I suspect that the real adults are sneering at my naivety. Sometimes, briefly, I’m sure I know what I’m talking about, and feel confident that I’m right about the world, because I do, after all, have 72 years’ experience of life. I can remember rationing and my tables, but I can’t remember new facts, figures and names to back up my ideas, because the old brain can only hold on to them fleetingly. I get all the details together in my head but then poof! They’re gone. Can’t prove anything. Can’t demonstrate that I’m a serious person. So I crack jokes. Sod it. Why not have a laugh on my way down the pan? But it’s a nerve-racking stage of life. I feel more and more frightened, because it’s a race against time. My outer casing is rotting away at top speed, before the inside has properly matured. Will it ever catch up with the outside? I don’t think so.

June Eric-Udorie: I feel middle-aged – 35, maybe?

Everybody wants me to be a “normal teenager”. My family joke that my sister is “normal” because she’s 14 and acts 14: she binge-watches television and talks about her crushes. I hardly do that (well, not a lot, anyway). And when people meet me, they’re always shocked that I was born in 1998, not 1978.

I’ve never really felt my age. When I was two and most children were singing nursery rhymes, I was singing No Ordinary Love by Sade. When I was only nine or 10, I read Judy Blume’s Forever, much to my mother’s horror. Teachers tried to reassure my parents that I was just mature. Some people have called me wise beyond my years. To others, I’m just plain weird.

A lot of people think I am older than I am. I get the odd look, the raised eyebrow, when I say I’ve only just turned 17. But I feel middle-aged: 35, maybe? That’s the age my mother reaches for when she angrily says, “I want my daughter to be 17, not 35!” My parents scold me because I say things you should say at 50. When my sister cried about not going to a birthday party, for instance, I said the world would not end and there would be many, many more parties.

Now I just laugh it off. When the lady in the supermarket overheard a conversation and asked if I was 30, I laughed. When I try on a dress and my friend remarks that only spinsters wear clothes like that, I laugh. I embrace it and no longer get upset.

I may be 17 biologically, but I swear I am older. I must be older. There are times, of course, when I sigh like a proper teenager on seeing my future boyfriend – I’m sure of it – and walk past him. But other times I go to meetings and discuss risk registers or wear clothes even my mother wouldn’t be caught dead in. That’s just who I am – age really doesn’t matter that much.

Bidisha: In many ways I am an advert for how not to age

I’m 37 at the end of this month, on the anniversary of Charles and Diana’s ill-fated marriage. In the lead up to the royal wedding our art teacher ran a competition to design a bridal dress. My friend Delilah won. I absolutely believed that her drawing would be made up and worn by Diana on her wedding day and was disappointed, when watching the TV, to see that the final product looked nothing like Delilah’s original vision.

I am happy to report that my childhood enthusiasm and credulity (and interest in fashion) have stayed with me until 40 is facing me like a … well, like a glass ceiling.

Now I am not sure how to pitch my behaviour. I treat women and men of my own age with benign indulgence, as though they’re my grandchildren: “Thank you dear. So lovely. Remember, say yes to life!” When I’m friendly I feel I’m being girlishly desperate. When I try to be all sociable lifestyle chic, like a living embodiment of Red magazine, I feel like a no-career lady that lunches.

This is the age at which you look at things rationally and make serious choices to shape your life, because there’s no time left to muck about. But, afraid of making a mistake, I did nothing. I waited, and of course nothing happened. I don’t fancy men and don’t want a partner, but I would have liked a daughter. I have no way of moving out of my mother’s home as I don’t earn enough. Living at home at 30 is cute. Living at home at nearly 40 says “serial killer with pathological oedipal complex”.

Every single afternoon when I wake up the same thought runs through my head. “What happened to my 30s? How did they pass so fast? How did I let them go like that?” In many ways I am an advert for how not to age, how not to manage your life. My elegance and vivacity are an exquisite, thin enamel concealing my panic. So you could say I’m feeling my age right now, right down to the last day.

Simon Hattenstone: I never did that grown-up, proper man crap

My neck is stiff, and doesn’t really move left or right much any more. It’s achy and embarrassing – when I look round at people I do it so slowly that I look like an inept stalker. When I run or go to the gym I’ve given up pulling my ankle back to my thigh because it goes nowhere near. I remember the great Nancy Banks-Smith wrote that you know you’re getting old when you can’t balance on one leg to get your undies on. Well, now I’m in my 50s, and I topple over sometimes.

Last week I found the first liver spot on my forehead. I rubbed and rubbed but it wouldn’t go away. My younger daughter asked what it was. She was upset when I told her it was an age thing. “Look,” she said, “it’s dirt.” She started rubbing, too. But she gave up soon enough and hasn’t mentioned it since. My back has started getting hairy after 50 pristine years. I reckon the hair from your head whizzes down an invisible chute before finding its resting place in your ears, nostrils and on your back. Ugh.

I’ve started appreciating the beauty of ungreyed hair – the reds or blondes, browns and blacks that you never thought twice about when you had it. I can’t believe I never grew a beard when I had the potential for pure unadulterated bearded blackness. I walk past shop windows and wonder who the slightly bent, pregnant man is before realising it’s me. People say the 50s are the toughest in terms of identity. Neither fish nor fowl.

So how old do I feel? About nine. I don’t feel slightly younger than my years because I never really did that sensible, grown-up, competent, proper man crap. I don’t feel like I’m in my late teens or 20s because I wasn’t relaxed in myself then and don’t hanker after those years. I feel nine in the way that I like to repeat myself, make up jokes that I know aren’t funny (“That was just a joke without humour,” I tell my children), hang out in my pants and a vest, do kick-ups for hours on end in the street, swear lots and think it’s clever, assume that people always know what I’m thinking so reckon I better tell them anyway because it’s “honest”, eat Smarties, drink Ribena, catch round things in my mouth from a great height, sing songs about Uncle Billy and his 10-foot willy, and ask if I can ring the school bell when I go into my daughter’s school (no, she’s not a pupil; she’s a teacher).

Most of the men I know of my age (and it is mainly men) seem so certain and self-possessed (or maybe they’re just good at acting like they are). They give the impression they know the answers to the world’s problems, feel that they are leaders or should be, and that others will always benefit from their wisdom. I still feel vulnerable, ignorant, sometimes shy, sometimes stupidly loud. I still want chocolate and raspberry sauce on my 99s, and I still want to stick my tongue out at the world. Despite being physically diminished like many a fiftysomething, nine is a pretty good age.