Experience enriches fiction, but it doesn't reward authors

At a certain point in your career as a novelist, you have to come to terms with no longer being "young". For novelists, youth seems to last, officially at least and according to Granta, until you are 40 – but eventually, time catches up with us all.

Personally, I've always been conscious of death, and on the whole rather cheered by the thought that one day my troubles large or small will be over. What I'm not so happy about is not having done enough with my life. Next to those I revere, composers especially, none of us will ever do much – or indeed, suffer as much. But there are times when I feel that I've been serving out a sentence of some 20 years in order to look after my children and work and write, and that none of these has been done quite as single-mindedly or as satisfactorily as I'd wish. Not that I'm complaining: I count myself unbelievably lucky to have combined even two of these things. However, other women artists may understand when I say that it's often felt like competing in a race in which you have a handicap.

About a decade ago, I looked up how old all the women novelists I most admired were when they published their breakthrough book – the book that either won them a big prize, or became a bestseller. I was quite depressed at the time, and wondered how long I was going to have to wait and whether it was ever going to be worthwhile. (Usually, I feel that one must write for the love of the thing itself, but this requires a level of fortitude that isn't easy to maintain.) Time and again, I found that they all hit their late 40s or mid-50s before this happened. The exception seemed to be gay women. The reason why was easy to guess: if you have children, your career tends to be eclipsed for a good decade-and-a-half.

Children bring plenty of other things to a novelist's life, many of which are beneficial, but the one thing that you can't get over is the loss of time and energy. There are only so many hours in the day. Even JS Bach, who crammed more compositions into one year than most would manage in a lifetime, and who had 12 children, had somebody else to do the dishes. Without children, many people could write a novel a year, certainly one every two years. With them, you more or less double that. The whole books-and-babies issue was satirised by the French critic Roland Barthes, who completely failed to understand why French novelists featured in Marie-Claire were photographed with both. I am not going to go into this vexed territory again, but I have been thinking a good deal this month about middle age, partly as a result of reading Jane Shilling's The Stranger in the Mirror, an affecting memoir of her own entrance into the condition of not-being-young.

Becoming invisible is actually quite an important thing if you are the kind of novelist who is above all interested in people, and I don't mind it as much as some. It means you can, like Miss Marple, be overlooked as you overhear all kinds of interesting stuff; personally, I found it quite annoying and tiresome to be looked at as a young woman (unless it was by someone I wanted to pay attention to me). However, not being young is currently disastrous for novelists, especially women novelists – much as it is for actors. Unless and until we get to the lofty eminence of our eighties and are once again deemed as interesting as Diana Athill, middle age is a period of about 30 years in which somehow, despite having a lifetime of experience to draw upon, we are somehow not worth reading.

This is, I think, a relatively new problem. Up until the 1980s, it was expected that novelists would be people of some age and experience. In fact, I remember when I met Graham Greene as a mere strip of an 18-year-old and said (with a mixture of trepidation and callow eagerness) that I, too, wanted to write fiction, I was subjected to one of his withering put-downs. "What can you possibly have to write about?" he asked. "You haven't begun to live. Wait until you're at least 40."

Nowadays, I might well say the same thing myself to a teenager – but I'd be wrong. I think the young have a lot to write about, much of which we tend to forget when older. I love the freshness of young writers, and the way they're still so exposed to painful feelings; I love the mistakes they make, and the violent extremes of emotion. Adults are so often so nasty to the young that they forget, the young can be just as observant and as critical back.

However, in one sense Greene was right. As a young writer, or even a writer of 30, you are unlikely to have the understanding of human nature and the experience of the ironies of life to draw upon. Having reached the grand old age of 51, I now see so much of life which is very like fiction – people who reappear after vanishing for decades, stories that are unexpectedly completed or enlarged, plotlines that converge or diverge as death, decrepitude, divorce, inheritance and a host of other factors familiar from classic fiction come into play. In middle age, most of the unworthy impulses that might inspire a work of fiction have fallen away; I am no longer interested in heroes or heroines who are as dazzlingly attractive or accomplished as I once wished to be, or as rich, either. I am simply interested in people. I could live twice as long, and never get to the end of how interesting individual lives are to me, or how interesting the novel is as a form. (I am not interested in experiments in form because on the whole this has been done before, is just showing off, and not as interesting to re-read.)

Furthermore, most if not all the contemporary novelists I most enjoy and admire – Linda Grant, AS Byatt, Rose Tremain, Lorrie Moore, Alison Lurie, Julian Barnes, Ian McEwan, William Boyd, Michael Arditti, Pat Ferguson and more – are middle-aged or older. They have life under their belt. They have seen and experienced things that make their fiction wiser and deeper than a person under 40 could write.

Yet it's also very clear to me that publishers would far rather I were some stripling of 25. Novelists now regularly get cosmetic attention for their teeth (Martin Amis is excused, because his really were a medical necessity). We all, if female, discuss plastic surgery with increasing urgency and interest, and every so often one or two disappear and return looking strangely fresher. Two novelists I know of have lost half their body weight by joining Lighter Life. One has had gastric surgery. Naturally, I'm not going to say who any of these people are – and nor do I mock them. Publishers are business people with stock to sell, and alas, it's always easier to sell something with an attractive person behind it than not.

However – I return to the point I've made before. On the whole, good and great fiction is not written by beautiful people who feel successful. It's written by the person who is most overlooked, all their life, and who understands things about the human condition which is very different from that of the experience of the 25-year-old part-time model. Every author has a professional deformity – club feet, an uncomfortable religious inheritance, short stature, or incurable alcoholism, take your pick. A writer is always an outsider, who has much less in common with a photogenic celebrity than with a bag-lady who rootles through bins muttering to herself.