We all know that teenagers are a fickle lot, and no one understands this better than the record business. With the market for prepackaged acts saturated - a manufactured band now stands little chance of success without the backing of a TV talent show - music A&Rs have spotted a gap.

Pop fans are growing up. Girls who were once hooked on Britney Spears and Steps are older and more picky. Now they want an artist with substance, not just a boob job and a big smile. More importantly, they want an artist they can relate to; they need someone who understands them.

Enter a new breed of pop star - serious singer-songwriter, troubled teenager and hot babe rolled into one. Over the past year we've seen the fright-wigged Pink and Canadian tomboy Avril Lavigne win over legions of teenagers with angst-ridden teen-pop. Now hordes of comely young singers are trying to ape their success with earnest guitar-driven ballads about teenage dysfunction.

Leading the British hopefuls are Bournemouth-born 16-year-old Amy Studt and 18-year-old ex-Sugababe Siobhan Donaghy. Studt had a musical upbringing - she studied oboe, piano and guitar - and has been writing her own songs since an early age. Like Lavigne, she has cultivated her own look - Lavigne wears skater chic, Studt has a penchant for thrift-shop threads - while her single Just a Little Girl ("Cause I'm just a little girl you see/But there's a hell of a lot more to me") is perfectly pitched at put-upon teens.

Donaghy is a pop veteran, having scored the Top 10 hit Overload with the Sugababes when she was just 15. She left the band in 2001 citing all the usual reasons - exhaustion, depression etc - and she is now striking out on her own in a new guitar-pop direction.

Rising across the Atlantic are the pouty Pennsylvanian and ex-ballerina Vanessa Carlton - think Alanis Morrisette minus the yodel - and 19-year-old Michelle Branch, a sensitive singer-songwriter who released the hit single Game of Love with the grizzled guitar hero Carlos Santana, and who claims her songs come to her in dreams.

Unlike Britney Spears and Christina Aguilera, they are presented as bona fide songwriters driven by a love of music and in control of their destiny. They are a marketing man's dream - artists with market value and a perceived artistic credibility.

The record industry stumbled upon this sales opportunity almost by accident. Pink's record label Arista originally had her down as an R&B singer, but buyers proved resistant. For her second album, M!ssundaztood, she underwent an overhaul, to emerge as a pseudo-grunge, angst-ridden rocker. Pink was distanced from her pre-packaged peers in her songs, too.

"Don't compare me to damn Britney Spears," she snarled in Don't Let Me Get Me. Her target audience was the post-Britney crowd: 14 to 18-year-olds seeking watered-down rebellion. This same audience snapped up Avril Lavigne - squeaky-clean teen disco was out, the guitar-wielding singer-songwriter was in.

Authenticity, or at least the appearance of it, is crucial to these artists' success. Fans are supposed to imagine them shut in their bedrooms, earnestly pouring out their lyrics and reaching out to like-minded adolescents. Yet it is not clear exactly how much they contribute to their own songs.

Lavigne's first three hits - Complicated, Sk8er Boi and I'm With You - were co-written by the Los Angeles hit-making trio The Matrix. Similarly, Amy Studt has been sold to us as a gifted songwriter, yet her forthcoming debut False Smiles credits an array of co-writers, among them Rob Davies, the pen behind Kylie's Can't Get You Out of My Head. Tellingly, her manager is pop Svengali Simon Fuller, inventor of the Spice Girls and S Club 7.

Nor does their music quite tell the truth. Lavigne's songs about teenage dislocation suggest a troubled upbringing; in fact she is of middle class and devoutly Christian parentage. This is a girl who holds her mother in such high regard that she won't swear in her songs. Teenage rebellion has never sounded so sanitised. Studt's album is what you might call Lavigne-lite. With the exception of some mushy ballads, each track adheres to the same formula: a slow-building verse followed by a punchy, singalong chorus.

Then there is the small matter of image. Of course, real musicians don't debase themselves by baring their flesh - Av-Lav famously announced: "I won't wear skanky clothes that show off my booty, my belly or boobs." Yet the singer's skate-punk look - heavy eyeliner, low-slung combats, school tie - has a stylist's hallmarks. As for Studt's faux-hippy chic and Pink's kiddiepunk aesthetic, let's just say it's unlikely that they do their own shopping.

But the kids have fallen for it. Pink and Lavigne are now multi-millionselling artists, as well as teen pin-ups, and where they go, Studt and Donaghy are sure to follow. Ironically, some of these singers have more in common with Britney then they would care to admit.

Not only has Lavigne been photographed for the front cover of Rolling Stone looking like a latter-day Lolita (though, unlike Britney, she kept her clothes on), she is also starring in her own movie. Doubtless the success of the Spears vehicle Crossroads led Avril's people to sign her up for Sk8er Boi - The Movie (still in its early stages).

One of the more depressing aspects of this new generation of pop princesses is their apparent belief in their outsider status. In their own minds, they are groundbreaking musical auteurs railing against the corporate machine.

It has probably never occurred to them they are mere pawns in a record-industry master plan and that, in reality, they are just as disposable as the pre-packaged acts which they so fiercely reject.

Amy Studt's album False Smiles (Polydor) is out on Monday; Siobhan Donaghy's single Overrated (WEA) is released on 23 June.