The gender-dependent development of moral exclusiveness

Men are more morally exclusive than women. When and how does this difference emerge in human development? Across four samples spanning the ages of 4 to 80 (total n = 1,842), we measure people’s moral exclusiveness toward human outgroups and non-human animals. We identify adolescence (13–18 years) as key: older male adolescents are more morally exclusive than younger male adolescents, while there is no such difference for female adolescents. Linked to this is a general preference for social hierarchies in males. We further find the turning point in gendered moral exclusiveness: while males are already more morally exclusive than females at the age of 6 and such gender differences persist throughout childhood and in adulthood, they are not yet evident in younger children. Resonating with literature in social-developmental psychology and evolutionary accounts, we suggest that gender differences in moral exclusiveness are likely biologically prepared yet strengthened through gender-dependent socialisation.