Young children's understanding of a biological basis for parent-offspring relations

2 experiments evaluated whether young children understand that kinship implies, but does not guarantee, physical resemblance among family members. In Experiment 1, preschoolers expected adopted babies to share physical properties, but not beliefs and preferences, with their biological parents rather than with their adoptive ones. However, preschoolers in Experiment 2 recognized that shared properties per se do not guarantee kinship: a baby who looks like and lives with a woman is not her biological baby if he or she initially grew inside someone else, whereas a baby may neither resemble nor live with its biological parents. Overall, the results suggest that children expect parents and offspring to share physical properties, but understand that shared properties do not necessarily entail kinship. In both experiments, the extent of this understanding increased with age. However, preschoolers' overall performance supports the claim that some children at this age have a naive theory of biology. The results further suggest that the critical development in an understanding of kinship is acquisition of factual knowledge rather than structural change.