In the second of a series about young people around the world as part of the BBC's Generation Next season, the BBC's Robin Lustig asks if teenage rebellion is a natural phenomenon or nurtured by Western pop culture.
The shop at the end of the street where I live in London has a sign on its door: "Only two children allowed in at a time."
The shop sells ice cream and canned drinks, and the shop-keeper knows that if crowds of children rush in together, some of his stock will disappear off his shelves into pockets and school-bags.
But if you think there is something new and frightening about children behaving badly, think again.
More than 2,000 years ago, the Greek philosopher Plato wrote: "Of all the animals, the boy is the most unmanageable."
These days, of course, in an age of sexual emancipation, what is true of boys is equally true of girls.
So why are so many children and teenagers so much trouble?
Is it something unique to the world's richest countries, or does the spread of globalised media mean that disruptive adolescent behaviour is spreading across the planet?
Confused but eager
At the University of Pittsburgh in the US, developmental psychologist Beatriz Luna has been analysing how adolescents' brains work to try to work out why they behave as they do.
And she says the answer is in a bit of the brain called the prefrontal cortex.
"It doesn't do anything particularly itself," she says.
"It just organises and arranges everything else in the brain. And what we find is that adolescents are showing an almost exaggerated dependence on prefrontal cortex, where the adult doesn't need to."
In other words, teenage brains are not as effective as adult brains at working out how to behave.
They are not too good at assessing risk, and they are particularly ill-equipped to analyse competing demands on them.
But according to another American academic, Cynthia Lightfoot, who has also made a study of adolescent behaviour, taking risks is not necessarily something that teenagers do simply because their brains are not fully developed yet.
"An awful lot of adolescent risk-taking is in fact incredibly rational," she says.
"Much of it serves important developmental functions such as exploration, learning about yourself, and learning about the world."
Rock and TV
A group of young musicians I met in India were doing a lot of exploring and learning about themselves.
Slapping and weeping - young Indian rockers
Trey, Shikan and Jonathan called their band Bitchslap, until they decided another name might be more suitable.
So now they are Lachrymosa, a Latin word meaning "weeping", that they picked up from Mozart's Requiem.
They say they are "just frustrated kids", playing loud, raw music modelled on American rock bands. Are they rebelling? Maybe, they say. Against what? They are not sure.
Western influences are everywhere.
In Ghana, in west Africa, I met a worried father, Madeez Adamu Issah.
Everything is changing because of the impact of television, he said:
"We watch American Idol, we watch what is happening in Britain, and then children here want to behave the same way.
"In the past, you had to show respect to your parents, you had to be careful how you talked back to adults - now it is no longer the same."
In Delhi, I met Reinu and her husband Mahesh and their two very Westernised kids: their son Trishang, who is 10, and their eight-year-old daughter Suhalb.
Trishang loves American video games - "I love America, it's my favourite country," he says - while Suhalb plays with blonde American dolls.
Reinu told me: "The environment here is so influenced by Western culture these days that even if you try to keep them away from it at home they'll be influenced when they go out of the house."
"It's everything," said Mahesh.
"Your clothing, your eating habits, everything. I don't know what is so special about Western culture that you get attracted to it without any self-control.
"They have all the powers now. They make us feel that we are not giving them everything that they want.
"We have to give them that culture, knowing that it will spoil them and that they will lose their own culture."
So what is it about Western culture that seems to encourage adolescent rebellion?
The American academic Cynthia Lightfoot suggests part of the answer may be connected with the fact that teenagers now spend much more time with each other than they do with adults.
"When kids are cut off from adult society they begin to affiliate with each other in ways that historically they did not," she says.
"With the advent of formal education, kids are more isolated from the adult world than they have been in the past. They also spend a lot more time with other kids.
"So this creates the conditions for the emergence of a youth culture or a peer culture.
"And as kids interact with one another, their group affiliation shifts from being primarily the family group to being the peer group."
Perhaps we should think of adolescents as children who are practising to be adults?
They make mistakes, and sometimes they break the rules - and as more and more of them, even in countries like India and Ghana, are exposed to the influence of Western youth culture, well, they are bound to want to try it for themselves.