Do clothes really make the man (or the woman)?

Some victorian - I always thought it was four-square, bearded Thackeray but my dictionary of quotations ascribes the saying to a certain Miss CF Forbes - once observed: "The consciousness of being well-dressed gives a feeling of inward tranquillity that religion is powerless to bestow." Anyone stepping out for the first time in a particularly flattering, rather too expensive, brand-new suit knows how right Miss Forbes was. You look good - perhaps not quite as good as you think - and so you feel good.

Some victorian - I always thought it was four-square, bearded Thackeray but my dictionary of quotations ascribes the saying to a certain Miss CF Forbes - once observed: "The consciousness of being well-dressed gives a feeling of inward tranquillity that religion is powerless to bestow." Anyone stepping out for the first time in a particularly flattering, rather too expensive, brand-new suit knows how right Miss Forbes was. You look good - perhaps not quite as good as you think - and so you feel good.

The outer you is transformed by its new clothes: but the inner you must surely remain unchanged, since your own particular bundle of genes and gender is fixed at birth and can't be affected by what you wear. Yet even if clothes can't radically alter us, we continue to behave as if they could. We select and refine some vision of an ideal inner self and dress the outer self accordingly. We use our clothes to send signals - this is who I am: which usually means, who I'd like to be.

The latest idea in voyeur television from Channel 4 sets out to examine how far clothes can affect the sense of our own gender. If a man wears a skirt and high heels, will he not only behave more like a woman and feel more like a woman, but actually become more of a woman? C4 has commissioned a series of three programmes installing a group of strangers in a house - but this time, the two men will dress as women while the women wear men's clothes. Putting several strangers under one roof and letting viewers eavesdrop on what ensues has become a popular formula. It's the cross-dressing that will make this series different.

The commissioning editors claim this is a valid experiment into the nature of gender. Presumably, for it to be significant, they'll have to choose manly men and womanly women; people scoring at the extremes of gender; rather than hovering somewhere towards the middle as most of us do. Obviously they hope viewers will be curious to observe the humorous or humiliating changes in behaviour this cross-dressing provokes.

Are macho men wearing dresses any more likely to clean the loo? (Much more interesting: will they lift the seat - and put it down afterwards?) Will fluffy women in ties and Y-fronts (presumably that's what they'll wear, having already annexed most other male garments) be more likely to pile the dirty dishes in the sink and think that means they've cleared up? Or will everyone behave differently only because they know they're on camera and can't help playing to it?

My guess is that if you made four men and four women swap clothes for a month, once they'd got used to the idea and stopped sniggering they would behave - at least in private - very much as they always did. The whole point of cross-dressing is that the transvestite knows that at the touch of a wardrobe door-handle he can change back. He doesn't want to become a woman; he wants to feel like a woman, be admired like a woman, walk like a woman, by wearing the kind of soft, clinging pretty clothes, make-up and underwear that he attributes to women. (You never see transvestites in T-shirt and jeans... that would destroy the whole point of the exercise.) Being a trans-sexual - someone who really wants to be the opposite sex - is a much more laborious process.

But clothes express far more about us than just our gender. Encountering dozens, even hundreds of strangers every day, there isn't time to get to know them in any real way. We rely on instant guidelines to help us make up our minds, and appearance is the first and most obvious guideline. Teenagers categorise themselves by their tribal dress - Newcastle football strip or designer gear; studded leather or sagging Chinos. Women proclaim their chosen identity with high heels or Birkenstocks; faded jeans or a tiny chiffon skirt. A man in a bowler hat looks - and is - a quite different sort of male from the one in a reversed baseball cap, as William Hague discovered to his public humiliation.

Different theories about what most defines us are regularly trotted out. Some claim that our friends ("peer-group") are the deciding influence. Freudian psychiatrists tell us it's our parents. Others - dieticians, vegetarians, the macrobiotic brigade - say the kind of food we eat can make us aggressive, dyspeptic or serene. The financial pages assume the crucial factor is how much money we make.

Few ever state the obvious: that while all these affect us, our genes were determined long before we were born and they decide our innate character and abilities. Experiments are devised to explore the various theories. Around Christmas a guilt-inducing television programme is dreamed up; wardrobe togs out a respectable businessman like a beggar; puts the beggar in a three-piece suit and, lo! People treat them quite differently. A beggar is only a beggar if he looks like a beggar. The businessman is usually the more surprised of the two.

Purists such as the early boiler-suited feminists deplored the power of clothes. They claimed that not only do so-called "feminine" garments present women as the helpless playthings of men; tight corsets and vertiginous heels literally made women defenceless, easy victims of male exploitation. Men claim to have been misled by such clothes and plead provocation as a mitigating factor in rape cases. Yet after more than 30 years of enlightened feminism we still don't dress like peas in a pod, though the Chinese in their Mao suits managed it for several decades.

Here in the West we continue to flaunt our individuality, casting our clues upon the waters... look, I wear black; therefore I am chic, sophisticated, stylish, worldly, slim. Look, I wear high heels: therefore I am frivolous, fun, fashionable, feminine. Don't look - I'm wearing beige; I want to blend into the background, be unobserved. The multi-billion dollar fashion industry relies on changing the way people dress, twice or even four times a year. How, without their customers' connivance, could they persuade a gullible public to buy new clothes when they already possess more than enough? It has to be because women - and, increasingly, men as well - believe that fashion does more than just present the wearer attractively. They must believe that garments can literally change you.

Thanks in part to Madonna's genius for reinventing herself through her clothes, the new feminists, too, have changed tack. They have decided that it's OK for women to dress provocatively. Bustiers and fetish corsets have become a way of proclaiming women's pride in their own sexuality. Far from using clothes to disguise their gender or adopt an anonymous asexuality, women's clothes now emphasise just how female they are.

They haven't quite reverted to the wasp-waists and whalebone of the Victorian era, when underclothes were so constricting that women were literally deformed by them. The new lingerie is shaped by clever synthetics developed in spacecraft to curve and redefine. The theory is that they don't have to hurt. In practice, you hear a very different story in the ladies' loo at any night-club, as women sigh and wriggle and try to ease their underwear into fitting more comfortably.

Will the chaps in Channel 4's new series agree to wear wired corsetry beneath their dresses? And if they do, will they feel more obliged to do the housework, more like women? My guess is that they'll rebel against both within the first week, cast their bonds and do what they always did. When the programme is shown next spring, we shall find out.