Abstract
While traditionally adolescent sexually harmful behaviour (SHB) has been considered beyond the domain of general delinquency, many adolescents showing SHB also show a pattern of non-sexual offending. It was hypothesised that an early onset of SHB would probably reflect the presence of developmental risk factors associated with a generic and persistent antisocial trajectory. A retrospective file review of cases referred to a national SHB service was conducted. Cases were categorised as early onset (n = 100), with SHB evident prior to the age of 10, or late onset (n = 137), with SHB first evident after the age of 10. The early onset group were found to have higher rates of maltreatment, poor temperament, aggression, hyperactivity, educational difficulties, and mental health problems. They also displayed greater continuity of non-sexual antisocial behaviour across childhood and adolescent periods, and scored significantly higher on a standard psychopathy measure. We propose that an early onset of SHB may act as a clinical marker for a group of children at risk of a general delinquency trajectory. These children require early and multifaceted interventions beyond those addressing sexual behaviour problems alone.