MY friend Janet is constantly IDd - in pubs and clubs, when she buys alcohol, for kitchen knives.

She hates it. Hates it.

Complains about it like they've insulted her mother, which I suppose, in a way, they have given that Janet is IDd because she looks so darned young and she looks so darned young because that's the way her momma made her.

I digress. My friend Janet is asked for ID constantly and she is black affronted each and every time.

I am almost never asked for ID. On the rare occasion a supermarket worker, say, asks for proof I'm over 25 I kiss them, square on the chops. I love to be asked for my ID.

I bring my driver's licence out of my wallet in an extravagant fashion and wait with glee for the ID requester to feast their eyes on my date of birth.

The difference is that Janet is really quite happy with her lot in life, she's proud of her acquisition of years and is sick to the tonsils of being patronised. She wants to look and feel her age.

I am a chronic underachiever and so to be assumed to be younger than I am is a second chance at success. I love being patronised for looking a bit younger than I really am - it's an excuse for being a bit useless.

I was reading about a long term study being carried out in Dunedin, New Zealand, that looks at the biological age of 1000 38-year-olds who researchers have been regularly testing since the age of 26. Some of them appeared - following tests on areas such as liver function, heart health, telemere length and cholestoral levels - to be still 26 while another, an "extreme case", had the biological age of a 61-year-old.

I was interested to note that the researchers seemed not to take mental age into account. Does attitude have anything to do with regressing or increasing the physical ageing rate of a person?

I wonder, if they tested Janet and I, would they find I had the characteristics of a 40-year-old while Janet is still rocking 21?

I'm definitely no generational spring chicken.

I'm heading up to T in the Park this weekend and just the thought of it exhausts me. All those young, slender things in denim shorty shorts who appear to feel no fatigue and no sense of their youthful power. I'd much rather be indoors with a book and a good pot of tea.

The Dunedin researchers now plan to sift the gathered information to find out which factors each group - the younger-than-they-ares and the older-than-they-ares - to find out what they have in common. This could be the secret of the fountain of youth and I will be waiting at the front of the queue with a jeroboam.