We found no effect of biological relatedness on punishment. Participants who thought a child's biological mother endangered her child were just as harsh in their punishments (M = 39.9 months, se = 2.012) as if an adoptive mother had performed the same act (M = 38.348, se = 2.823, **d** = .024, 95%CI = -.268 to .315).
We did, however, find a significant effect of participant sex. Despite condition (interaction *p* > .205), women consistently punished a mother who endangered their child more harshly (M = 41.624, se = 3.12) than men did (M = 32.146, se = 2.675, *Beta* = .221, *p* = .004).