Explanations for criminal behaviour are as old as the types of behaviour themselves – debate and discussion about why people break rules have excited general and scholarly interest throughout history. Indeed most people have their own views as to what are the most likely causes of such behaviour; and these views are all likely to contain some elements of ‘truth’ without being complete explanations. Inherited defects, overcrowding, inadequate parental supervision and getting in with the ‘wrong crowd’, for example, have all been proposed as causes of criminal behaviour.