The largest cohort study on the development delinquency and criminality in the UK found that convicted delinquents are more likely to have experienced poor parenting, characterized by harsh or erratic parental discipline, neglectful parental attitudes, parental conflicts and lax supervision in their childhood. The statutory age limits adopted by juvenile courts, which deal with children and adolescents who have committed legal offences vary between countries. It is difficult to ascertain the true extent of child and youth offending due to the limitations of each information source. It is claimed that the prevention of delinquency, criminal behaviour and reoffending can be achieved by interventions that alleviate risk factors and strengthen protective factors. At the individual level, support for academic work and cognitive-behavioural intervention is provided for children identified as being at risk. Early intervention is preferable to tackling a young person's problems once they have begun.