Kenny tells me how much his parents hate it whenever he goes out with his friends at weekends.

I ask what he knows about their childhoods.

"My dad's dad was really strict," Kenny says. "He wouldn't let him do anything! And my mum went to boarding school."

Sophie wants to be a professional dancer but apparently her mum thinks this is a stupid idea. "My mum left school at sixteen," says Sophie, "and started working in a shop. She's been there ever since, working her way up. She's the assistant manager now."

Most adults have a powerful relationship with their own adolescence. Young people evoke in them strong feelings and reactions. In part, these reactions are complaining and scornful: young people are accused of being ungrateful, lazy, selfish, irresponsible.

It's hard to think of young people without thinking about our own unfulfilled potential. We see them happy, busy with their friends, making plans, and we think of all the opportunities we never had or, at least, never took; we think of all the idealism we once had but seem - now that we're older - to have lost. Watching young people grow up, we're reminded of the love we never had ourselves or feel that we were denied, of the fun, the friendships, the sexual opportunities. I think our envy is there all the time, lurking. Of course, it's not the only thing we feel - we love our children and we want them to be happy - but it's a secret feeling that we don't acknowledge, a feeling which subtly informs our behaviour.