* Testosterone has long been considered the main cause of aggressive behaviour. However, studies presented to the conference suggested that it was negative early-life experiences, rather than the increase of testosterone at puberty, that account for severe aggression in later life.
Dr Stephanie van Goozen from the universities of Cambridge and of Utrecht in the Netherlands, examined studies of aggressive behaviour in children with a range of anti-social behaviour disorders.
She found these children had the same neurobiological deficits as adults with serious conduct disorders.
