The XYY 'Super-Male' Myth and the Debunking of Chromosomal Determinism (1965-1993)
Summary
Methodological caveat. In 1965, Patricia Jacobs published in Nature a study linking the XYY karyotype (an additional Y chromosome) to aggression and criminality, conducted in a high-security Scottish psychiatric hospital. This 'supermale theory' was widely disseminated and subsequently DISCREDITED by large-scale population studies (notably Witkin 1976 in Denmark). The CHI (Klinefelter/Epstein) line of inquiry risks repeating this error by conflating XXY (Klinefelter, passive tendency) with XYY (discredited aggression theory).
Detailed context
Methodological caveat. In 1965, Patricia Jacobs published in Nature a study linking the XYY karyotype (an additional Y chromosome) to aggression and criminality, conducted in a high-security Scottish psychiatric hospital. This 'supermale theory' was widely disseminated and subsequently DISCREDITED by large-scale population studies (notably Witkin 1976 in Denmark). The CHI (Klinefelter/Epstein) line of inquiry risks repeating this error by conflating XXY (Klinefelter, passive tendency) with XYY (discredited aggression theory).