Did anyone actually like being a teenager? If some kind-hearted almighty decreed that, from now on, everyone would go to sleep aged 12 and wake up aged 20, would anyone really mind? If no one had to lose their virginity in the neighbour's shrubbery, or spend hours trying to get high on municipal hydrangeas, or wake up in a pool of Buckfast, or have to answer questions that ended "discuss, quoting relevant examples", would anyone feel a sense of loss? If no one ever had to read Sylvia Plath again, or worry about mobile phone fascias, or spend 25 minutes in the local chemist considering the choice between premature death and a packet of Lillets, would the world be any worse? In fact, why not just de-invent teenagers? Marketing men made them up, so, presumably, marketing men could just remove them.

Being a teenager isn't clever and it isn't fun. The government doesn't approve of them and the state doesn't count them. Schools just need them to pass exams so that they, in turn, can pass their Ofsted inspections. Adults - though they don't admit it - are scared of them, roaming the high streets of Britain in packs and herds and gangs. Life keeps making decisions for them - school, parents, the government, their own bodies - that they don't want and can't control. Siblings are useless, parents are embarrassing, peers are terrifying, and the only bit of advice anyone ever gives them is "it's just a phase."

Between the 1930s and the 1950s, things were so much simpler. If our parents are to be believed, everyone was poor, everything was rationed, and life was only available in black and white. Austerity extended to the emotions as well, and if you didn't like the childhood you got, then you'd just have to make do and mend. In retrospect, most of the postwar era came to sound like an SAS survival exercise: how to make one empty cotton-reel, a worm-eaten carrot and a two-litre can of high-grade aviation fuel last a whole childhood, and still have fun.

Then the 1960s gave us teenagers. Teenagers had needs, requirements, habits, and - most vitally of all - money. They were a distinct demographic, they had (their parents') cash to burn, and they had Issues. They could take their pick of things to complain about, from the Vietnam war to the Prague spring and - later - the beginnings of the Campaign for Nuclear Disarmament. They had adult hypocrisies to overthrow and whole worlds to change. They had something to fight against, and therefore they had something to fight for.

Now, there are no causes, only money and a kind of godless moral mud. As politicians have finally realised, most teenagers don't bother with politics. Non-voting can no longer be discounted as a one-off demographic blip, it's a fact and an unpalatable one at that. After Mrs Thatcher, no one voted for a better society any more, they voted for a better car or a smarter pension scheme. Teenagers, being the last ideologues, suddenly had nothing to believe in except a world without any kind of ideology at all.

To replace it, there was a new set of absolutes; you were what you consumed. Belief - except perhaps in Celtic, ketamine or Eminem - didn't come into it. Belief was, well, ... embarrassing. Besides, there has always been an odd disjunction between teenagers' outward radicalism and their inner conservatism. Outwardly, they may devote their lives to the overthrow of global capitalism or the Save Small Defenceless Rodents campaign. But at home, they're all miniature Mullah Omars, determined to prevent their parents from divorcing, their mother from considering a face-lift and anyone (except them) from having sex ever, ever again.

In the absence of causes, there are other pressures. More than ever, the teenage hierarchy is based on what you've got and where you belong. Before getting the attitude, you've got to buy the identity: indie kid or nu-metal head, rapper or sports-casual. Each persona has its uniforms, its strips and its narrow brand names. It is also often the case that teenagers dress for the body that they want, not the body they have, which is partly why it's not unusual to see a look designed for a six-foot flat-chested raven-haired space-goddess worn by a dwarfish redhead with acne, spectacles and a 34-FF cup size.

Nor does it help that no one can quite work out what the point of men is any more. For the last couple of decades, it's been taken for granted that there's nothing a man can do that a woman can't do better, and probably more cheaply as well. To be a girl in 2002 is comparatively easy; they've got the whole world open to them, they can take on any man and not get beat, and when things go wrong, they can still yell "oppression!"

The way that teenage girls deal with each other also has its uses. Generally, girls don't get what they want by fighting for it, they get it through guile, manipulation and the judicious use of psychology. If they want to bring another girl into line, they are unlikely to thump her into submission, they'll just erode her self-confidence. All those small, adolescent taunts - "how come you don't have a boyfriend? How come you've got a weird accent? How come you don't have any decent clothes?" - are more effective than a thousand beatings. There's other weaponry too: ostracism ("sorry we didn't invite you to the party - you wouldn't have liked it"), slurs ("she's just after your man") and friendly advice ("don't worry, you've just got big bones").

Girls are good at the feral stuff, in detecting the weak spots and then exploiting them. They also manage a double-edged morality, being both fixated with sex and giving each other a hard time for having it. "She's a slag/slapper/tart" isn't only something that boys say. It's also worth remembering how much this carries over into later life. All those celebrity magazines - Heat, OK!, Now - exist because girls, and women, have a rich appetite for bitchiness. Flick through Heat, and the commentary is just the same as it was all those years ago by the bus shelter: "She wasn't born with hair that colour; God, she's put on weight; look at that liposuction; Jesus, have you ever seen such a vile wedding dress?" Boys don't give a stuff if a girl gets the right brand of nail varnish, or Liz Hurley gets her pre-pregnancy figure back a week after giving birth. She's not doing it for them. She's doing it for us.

The qualities that have always been regarded as female - intuition, lateral thinking, a dreamless philosophical pragmatism - are exactly those qualities which the world in 2002 most values. Unlike boys, who retreat into the other-worlds of sci-fi or computer gaming, girls generally stay rooted in a reality, albeit one which includes growing up to be a corporate dominatrix and living happily ever after with Gareth Gates. Though both may be unfeasible, an interest in getting to the top of the business world has a lot more practical use in later life than an interest in getting to level 89 of Alien Death Fiend.

For boys, things just keep getting more complicated. Though there will always be a few eternals - there is always a gang, always a leader, always a loner, and always a hanger-on - some of the outward things have changed profoundly. Boys are still expected to be hard and to prove themselves physically, but they've also got to be tender, groomed, emotional. They aren't allowed strong adult role-models, because every adult - according to the papers - is now a potential paedophile, and because every advertising stereotype just makes them look like a bunch of unreconstructed idiots. And it's no longer any good just to slap on a leather jacket and a chinful of their father's Old Spice. They've got to look as pretty and as rich as girls while still riding like an outlaw through the badlands of SW17. Which, in practice, means worrying about getting knifed in the Reeboks down the club on a Saturday night.

Nor is home any help. There is a belief, started by Freud and helped along by Philip Larkin, that most bad things in life can be traced back to the family. But by the time you're a teenager, it isn't your parents who fuck you up, it's your peers. After all, it isn't your parents who ridicule your cheap trainers, or your miserable choice of music, or who force you to drink a bottle of tequila and pass out in a dog basket, or who destroy you for looking wrong or talking wrong or being interested in things that you shouldn't be interested in, like books, and De Beauvoir, and whether or not God exists. It isn't your parents who give you STDs or premature knowledge of the morning-after pill, or who ply you with odd substances that turn out, after many months of painful experimentation, to have been half-glass and half-Vim anyway.

Besides, part of being a teenager is to spend as little time in your parents' company as possible; to eat their food, sleep in their house, and spend their money while pretending to the outside world that they do not actually exist. Instead, you spend your time round at other people's houses, wondering why your parents are so mean they won't let you have a £5,000 drum kit in your bedroom, and convinced that your father's decision to buy a Honda Civic instead of a TVR is really a foul ancestral conspiracy to degrade you in front of your peers.

On the few occasions (Christmas, birthdays, death of family dog) when you do have to return home (late, and smelling of gutters) every conversation becomes the same: "Where are you going?" Out. "Who are you going with?" Someone. "What time will you be back?" Later. Slam. Siblings are no use, either. If they're older than you, they behave like Cinderella's uglier sisters ("You gave her a mobile! You never gave me a mobile till I was 17! That's so unfair!"), and if they're younger than you, they ask embarrassing questions ("How come you're always in the bathroom? Why's your voice gone all funny? Are you hairy down there yet?") and get in the way.

If anything really serious happens - divorce, death, drugs - there is no one you can talk to, because the only conversations you can have with your peers are about diets, sex and how drunk you got, and because you wouldn't talk to your parents, since parents are often the problem. Though Britain in 2002 is supposed to be a more expressive nation, there are still many places where emotions never reach. The oft-quoted but still dreadful statistic that suicide is the second-highest cause of death among young men between 15 and 24 conceals a more complicated truth: young men still don't talk, but they do drink more and take more drugs.

So, by all that is logical, the thing to do would just be to ban teenagers. Remove them from the registers, take them off the flow charts and the TV schedules, drop them from the public consciousness. Go back to a pre-Victorian age, when there were just adults and slightly smaller adults. Life would probably be better for us, and it would definitely be a whole lot better for them. And, if the world really does have to live with teens, then they should be issued with two pieces of information the day they turn 13; the worst teenagers make the best adults, and it really is just a phase.

· Bella Bathurst's novel Special will be published by Picador on October 11, priced £15.99.

The following correction was printed in the Guardian's Corrections and Clarifications column, Thursday October 3, 2002

We referred above to "the Prague spring and - later - the beginnings of the Campaign for Nuclear Disarmament". Prague Spring refers to the events of 1968. CND held its first public meeting in February 1958 (in time to support the first Aldermaston march which took place a little later that year).