 According to studies, children who knew many adult criminals were more likely to engage in violent behaviour by the age of 18 years than those who did not.Gang violence is often associated with carrying weapons, including in school.A study of 10-19-year-olds in the UK found that 44% of those who reported belonging to a delinquent youth group had committed violence and 13% had carried a knife in the previous 12 months versus 17% and 4% respectively among those who were not in such a group.