'In our early teens, we invariably lack self-confidence and gangs provide an emotionally secure environment in which the unwritten rules are well understood,' he says. 'Moreover, close relationships and a sense of belonging are crucial sources of happiness, and gangs foster these.' The association between teenagers and gangs is also a natural one. 'By our late teens,' explains Baylis, 'our self-confidence is probably sufficient that we're willing to trade our old gang for the social mobility of seeking out the most attractive individuals wherever we can find them.'