This week's big moral question is apparently: “Should a 15-year-old TV actress show her bare back and shoulders in a grown-up magazine?” I have another one: can't we be adults about this?

Miley Cyrus is the teen star of the Disney TV “smash” Hannah Montana, in which schoolgirl Miley leads a secret double life as pop star Hannah. Her budding stardom (Miley's, not Hannah's) is now threatened by a backlash after Vanity Fair published a half-naked photo of her wrapped in a sheet, looking coquettishly over her shoulder with bedroom hair and bright-red lips.

Let me declare an interest. “As a parent” I hate Hannah Montana, one of the sickeningly saccharine high school TV shows our young daughters love. It is all teeth and false tans and homespun moral philosophy dispensed by Miley's real and TV father, Billy Ray Cyrus of the deeply meaningful Achy Breaky Heart. I might cheer reports that Disney now plan to drop Hannah, but another one will take her place.

But there is more at stake here than trashy teen TV, or discovering “where Hannah ends and Miley begins”. The furore suggests we are all confused about where childhood ends and adulthood begins. With frequent rows about the alleged sexualisation of children, nobody seems sure where to draw the line any more. An apologetic Cyrus says she thought Annie Leibovitz's pictures would be “artsy not skanky”. But who knows where the art/skank divide might be when such a goody-goody popster as Miley goes on stage dressed like a “saucy” St Trinian's girl?

The problem lies not with children, but adults who have lost a clear sense of what it means to be a grown-up in a world of kidults, adultescents, mummy's boys and big babies. I thought the most “revealing” Vanity Fair picture was the creepy one of her on her 46-year old father's lap. Never mind the bedsheet, look at him preening in his long greased hair, sleeveless vest and tattoos. As Howard Stern says: “It looks like his daughter is his girlfriend. He's trying to be hot.” Little wonder that kids don't know how to behave if adults act like dorks.

Experts now warn parents that, as one psychologist says: “Miley is a role model for so many young girls, many of them as young as 5” and her behaviour could make them “put on sexy clothes, take a sexy photo or maybe even have sex”. What all this reveals, however, is not that Miley is a “bad” role model. It is the downright stupidity of the Mickey Mouse notion of meejah role models, the belief that some teenage squeaker could or should teach our children to sing from the right hymn sheet.

By all means hang Hannah Montana and tell Miley to put her top back on and wipe that muck off her face. But if we seriously think her “kiddie porn” picture will render parents powerless to stop the corruption of our children, or that execrable TV shows can provide lessons for life, then we really must be living in a Walt Disney world.

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