ONE OF MRS WINTERSON'S objections to literature was that “the trouble with a book is that you never know what's in it until it's too late”. To extract the full flavour of this dire warning, “book” must rhyme with “spook” and be allowed four extra Os.

When I challenged her with her own taste for murder mysteries, she replied: “If you know there's a body coming, it's not so much of a shock.”

As much of a shock as what? My mother never recovered from the fact that Jane Eyre doesn't marry St John Rivers, and to cushion me from a similar cardiac disappointment, she altered the end, so that when she read it to me, she simply carried on turning the pages, but making it up as she went along. I have to say it was a shock of a different kind when I read Jane Eyre for myself, but it was one of the things that taught me how to be a writer. Just make it up, and if it has been written already - make it up some more.

And so, my early years were spent dragging huge sacks of Ellery Queen Large Print Murder Mysteries from Accrington Public Library to 200 Water Street. Water Street is all uphill, and we lived nearly at the top, and there was I, always tiny, dragging my load, and there was Mrs Winterson, tall and enormous at 20 stone, standing at the front door, looking down the street with her binoculars. When I finally arrived, she would inspect the titles, and send me back if there was one she had read already. She inspected my titles too, always wary of seditious influences. Fortunately she had no idea how radical is Finn Family Moomintroll, or that she herself made a passable Groke.

Who was the first murderer in the Bible? A favourite Sunday School quiz question, and given the number of murders and sex crimes in the Old Testament, it is not surprising that Mrs Winterson favoured life's darker tones. Forgiveness was not something she understood, for herself, me, or anyone. It is something I had to find slowly, for myself, much later.

Let's say there are only three endings to any story, discounting happy endings as too Hollywood: Revenge, Tragedy, and Forgiveness. Crime writing feeds our feelings for tragedy and revenge, and we can fool ourselves that there is also such a thing as justice - that the end is just or that justice has been done, or that justice has been avoided, but we know what it is.

I am never sure about justice as an end in itself, because justice often seems partial, fashionable even, as our ideas of crime and punishment change. The great thing about Conan Doyle's Sherlock Holmes is that he has a very particular, and indeed peculiar idea of justice, which is always bound up with suffering and forgiveness. Those stories remain satisfying, I believe, because they activate larger issues of personal and collective responsibility. This cannot be said of Agatha Christie, whose yarns are entertaining enough but who is without moral capacity. Why she is so high on the Times list is more of a mystery than anything she wrote. Still, we have to remember that lists, like labels, are as partial as justice.

I never read crime fiction until I became friends with Ruth Rendell many years ago, when she lent me a cottage to write in. I had a prejudice against genre fiction - though time has taught me that it is the labelling that is the problem, not the fiction. Why are we always rushing to label things? If one more person tells me that my book The Stone Gods is science fiction, presumably because it is set in the future and has a robot in it, I will turn myself into a dalek. Books set in the past are not necessarily historical novels any more than books with a gay character must be queer fiction.

Of course there are whole warehouses of books written every day that are only and no more than dog books, horse books, romance, sea stories etc, but real books cannot be labelled in any meaningful way. Real books have to be read and reread, and they are life in all its variety. Those are the books I want to read, and I don't care about the label - or whether there's a dead body.

Mrs Winterson was right - the trouble with a real book is that it is affecting, because it is alive.

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