A 26-year-old man from Belgium, Loïc De Marie, has spoken publicly about being diagnosed with psychopathy, describing childhood incidents in which he felt no emotional response to danger or death, including watching his sister drown before eventually rescuing her with a golf club because he did not want to get his clothes wet. Speaking to Australian broadcaster SBS's Insight programme, he also recalled feeling nothing when a classmate died in a car crash, and later becoming involved in violence, including bringing a baseball bat to school intending to attack a rival. His case highlights how psychopathic traits, though not a formal clinical diagnosis, can be identified in childhood and managed through therapy.

De Marie, who now lives in Vancouver, Canada, sought help from a psychologist three years ago after years of feeling "different" from those around him, and was subsequently diagnosed with psychopathy, a term linked to antisocial personality disorder and traits such as manipulation, dishonesty and a lack of empathy. Researchers estimate such traits appear in roughly one per cent of men and 0.3 to 0.7 per cent of women. His father, Philippe, said the diagnosis helped explain years of troubling behaviour, while UNSW psychology professor Eva Kimonis noted that callous and unemotional traits can reliably be measured from as young as two or three, underlining the value of early intervention.