Can well-documented gender differences in evaluations of prosocial versus antisocial actions found in childhood and adulthood be traced to sex differences in basic sociomoral preferences in infancy? We provide an answer to this question by meta-analyzing sex differences in preference for prosocial over antisocial agents in a set of 53 samples of American and European infants and toddlers aged between 4 and 32 months (N = 1,094). Although the original studies were agnostic to sex differences, we were able to retrieve the original data sets and estimate the effect of infants' and toddlers' sex on sociomoral preferences. Employing both a standard frequentist and a Bayesian approach to meta-analysis, we found strong evidence supporting the absence of sex differences in sociomoral preferences among infants and toddlers. We discuss the relevance of this finding for theories and descriptions of the emergence and developmental trajectory of gender differences in morality.