Baby was a black sheep: Digit ratio (2D:4D), maternal bonding and primary and secondary psychopathy

• Low LH2:4D predicts primary and secondary psychopathy in women.
• Low maternal care predicts primary psychopathy in women.
• High maternal protection predicts primary psychopathy in men.
• Low maternal care predicts secondary psychopathy in men.
• Maternal bonding predicts primary and secondary psychopathy above and beyond 2D:4D.

Psychopathy is generally considered to be a male adaptation. While studies have elucidated a relationship to freely circulating testosterone, less is known about the role of prenatal testosterone (PT) in the development of primary and secondary psychopathy and how this pertains to sex differences. In this study (N = 148), digit ratio (2D:4D) was used to investigate the relationship between prenatal testosterone and primary and secondary psychopathy. In addition, quality of recalled maternal bonding was measured to see if postnatal experience could affect the influence of PT on psychopathic behaviours. Low LH2D:4D predicted primary and secondary psychopathy in women. In men, low maternal care predicted primary psychopathy and high maternal protection predicted secondary psychopathy. Low maternal care also predicted primary psychopathy in women. Lower levels of maternal care and higher levels of maternal control contributed to primary psychopathy above and beyond PT. Lower levels of maternal care were also an influential factor for secondary psychopathy above and beyond PT, although higher levels of mother control were not.