Here is one voice: “It’s so cool,” enthuses 16-year-old Sam. “I mean, she’s got, like, a tongue stud and a tattoo on her shoulder. I’m going to get that done - and dye my hair green. We all are, at half-term.” And who is we? “Oh, you know, all that gang, the ones I go to concerts with.”

Here is another: “The music business is dying because music has become too bland.” “Video games are taking the money,” says the industry spokesman, “because they’re what parents disapprove of.”

Imagine a forest, an urban forest, full of movement and sounds and the faint, intoxicating thrumming of danger. Carefully the parents guard their young, excluding all hint of harm, tending to needs, fine-tuning wants (Teletubbies? Or do you prefer Sylvanian Families? Adidas? Or Calvin Klein?), monitoring friends. There are gifts, there are treats. Adornment of the person and the surroundings consumes time and effort. Shopping brings families together, united before shop windows, cooing over purchases in special plastic bags. Some gifts are special. Jewellery marks birthdays: signet rings, gold crosses, silver charm bracelets, perhaps, daringly, an anklet. First earrings, little gold studs, appear daintily on toddlers, even on babies. “Sweet!” One day the young emerge. Outside the parental range, being sweet does not seem so desirable. Hormones throb through the air. Some of the chief emitters of hormones present an untamed look, a kind of anti-grooming. They are cool. Being sweet is the opposite of desirable. It is Not Cool. But how do you show you are not sweet?

Our social vocabulary remains the same: the currency of goods, grooming, gifts - but reversed. So you get ripped clothes, dreadlocks, piercings, assertions of difference that reject parental control.

The worst thing concerned adults can do is move into approval. Adult approval killed heavy metal music and long hair for most kids. After all, if your parents smoke dope, Dad wears a pigtail and Mum goes to pop festivals, rebellious adolescents must go further. So all that gulping and saying, well, yes, a belly-button ring is quite pretty really misses the point. As is the school that allows “no more than two piercings per ear”.

Really strict school rules - “Get your hair cut, boy!” - are much more agreeable. They allow the young person to revel in hating oppressive authority. As one parent I know said to her boy: “OK, so you hate me. That’s your job. Mine is just to stick around and be hated.”

So, it’s OK. You can be horrified by that tongue stud as much as you like. Tell them it spoils their beauty and may cause infections, while at the same time treasuring the knowledge that it is one of the most easily reversed body alterations. It’s quite a safe rebellion, really.

And, hey, in California, they say that patterned branding is the next big trend in body art.