It could be argued that the increasing contributions of genetics and neuropsychology in the last decades of the 20th century to the aetiology of personal characteristics has led to a more balanced consideration of causality in criminal behaviour, correcting the predominantly social deterministic model that has always sat uncomfortably with the incidence of ‘white collar crime’, which demonstrates the power of risk over cold intellect, as displayed by certain errant high-profile politicians in the recent past. Nowhere is the evidence for a strong constitutional basis to behaviour more compelling than in the research on attention deficit hyperactivity disorder (ADHD), albeit with potential exacerbation by malign environmental influences.