Among the major personality and behavioural factors that may predict youth violence are hyperactivity, impulsiveness, poor behavioural control and attention problems. Nervousness and anxiety, though, are negatively related to violence. In a follow-up study of over 1000 children in Dunedin, New Zealand, boys with violent convictions up to the age of 18 years were significantly more likely to have had poor scores in behavioural control (for example, impulsiveness and lack of persistence) at the age of 3–5 years, compared with boys with no convictions or with convictions for non-violent offences (74).