Evolutionary theory predicts humans to be more altruistic towards genetically more closely related kin. Because fathers face uncertainty about the relation to their children, the asymmetric parental altruism hypothesis predicts mothers to provide a higher share of parental care than fathers. We tested this hypothesis using parental choice experiments in rural Tanzania, in which fathers and mothers could choose between an outcome that benefited themselves and an outcome that benefited their children. When a parent was solely responsible for the outcome, mothers chose more altruistic than fathers. However when the choice situation was changed into a coordination game in which responsibility was shared with the partner, the sex difference disappeared. Fathers then chose somewhat more altruistic, but mothers substantially less. Our findings thus partly support the asymmetric parental altruism hypothesis, but they also show that parental altruism is influenced by the context in which choices are taken. © 2014 Vyrastekova et al.