Some authorities have called youth violence a public health issue, because it's like a virus that spreads from child to child.
Yesterday, I stood outside the Damilola Taylor Centre in Peckham, London and pondered again how we could have come to a situation where, in some European cities, violence by and against teenagers has reached chronic proportions.
We were filming a TV documentary on youth violence and the gang problem. It seemed fitting to stand near where, just a few years ago, young Damilola had bled to death after being attacked in a block of high-rise flats. Sadly, Damilola hasn't been the last victim of youth violence in the area, which some people are now calling 'England's Bronx.'
In the UK, one in six children say they've been hit, punched or kicked on the streets - and 7% say they've been attacked with a weapon of some kind. 60% say they've witnessed violence or bullying between young people. Meanwhile, one study has found that a majority of Britons are now afraid of their own young people.
It's not just the UK that's suffering, though. In France, in October of 2006, violent riots rocked several major cities; riots that were led by rampaging youth gangs. And in the US, young people between the ages of 12 and 17 are more likely to encounter violence than almost any other group.
So why is there all this violence among the young?
Two obvious factors are poverty and social inequality. Today's aggressive multiculturalism has many benefits, but it presents some real challenges when it comes to social inclusion. Most Europeans are proud of the levels of social integration in their societies, but many children of immigrants feel that the system is stacked against them.
This was the root of the riots in France, where in some places youth unemployment had soared to between 30 and 50 percent. Of course, unemployment breeds more unemployment. In some of our cities we're producing a core of young people who move into their 20s with a background of long-term unemployment, punctuated only by short periods of unskilled labour.
Many teenagers get little encouragement at home and finding a job offers the first great opportunity for them to feel productive. When they find there are no jobs waiting for them, they can get frustrated, angry with the system and powerless to change their situation. Often these negative feelings are stored away until they eventually break out in behaviour that's both antisocial and anti-self.
Another factor in the rise of youth violence is the abuse of alcohol and drugs.
In one London study, half of all the young people belonging to delinquent groups admitted their group had used drugs together in the last year. Drugs don't cause violence, but the two are linked because they're both part of a lifestyle that's built around high risk and destructive behaviour.
Kids get involved with drugs for all kinds of reasons. For some, it's all about the experimentation itself. Pushing the limits of safe behaviour gets the adrenaline pumping; so drug taking can begin as a kind of game. Taking drugs is also worn as a mark of independence, a way of gaining respect.
Of course, a lot of this experimenting with drugs begins with alcohol. We've seen a rapid rise in teenage binge drinking in Europe and it's left many people wondering why, in an age of unprecedented prosperity, young people are turning to the bottle in a way that puts their health, and even their lives, at risk.
For some alcohol is used as a coping mechanism, especially where there is a family history of child abuse, or emotional disturbance. But for others, consuming huge amounts of alcohol seems to have become a form of personal expression. It's almost as if they feel they can't be truly alive, or express themselves, until they've had more than a few stiff drinks.
Many young people drink too much only because they're bored. Not bored as in having nothing to do; bored as in having no long-term sense of existential purpose.
There are many other factors to consider when it comes to youth violence - including the links between gang culture and drugs, and the lack of government support for measures that would strengthen the traditional family unit.
(At present, some governments have fostered a 'handout' culture which often seems to make the breakup of a marriage seem almost as practically viable as holding it together.)
Surely it's time for some real soul-searching in our communities. Young people are not just our future; how we treat them is a representation of the kinds of people we are. It's time for us to re-evaluate how young people - especially in our poorest suburbs - see the world in which they live.
Surely it's time for those of us who are educators, business, media and community leaders and certainly politicians to involve ourselves more closely in solving the problems that work against a positive youth culture.
But most of all, it's important that those of us who are blessed to be parents try to engage with the world in which our young people move.
There's no denying that, at the end of the day, we as parents must accept a large part of the responsibility for how our kids behave. And studies have shown that one of the early reasons kids get involved with gangs is that they feel disengaged at home.
I've made presentations to parents' groups for more than 25 years and it's basically impossible to find parents who want to raise troubled kids. Everybody wants to do their best with what is after all a very tough assignment.
Engagement with teenagers always sounds easier than it is in practice. But it begins with simply remembering what it was like to be young - and trying to see the world through the eyes of our kids.
On its own, that won't turn society's youth violence problem around, but it may just help to keep a few more kids from feeling that violence is the only way to deal with frustration, or that the world at large cares little about the challenges they face.