The persistence of the gender wage gap suggests it may have roots extending back into childhood. Using data from a US longitudinal survey, this column examines how gender differences in adult earnings correspond to various childhood behaviours. Results indicate that women (but not men) who exhibited headstrong behaviour as children incurred significant earnings penalties as adults, while men (but not women) who exhibited more dependent behaviour as children were penalised. Whether these patterns are the result of nonconformity to gender norms and stereotypes warrants further attention and study.