Deterministic or probabilistic: U.S. children’s beliefs about genetic inheritance

Do children think of genetic inheritance as deterministic or probabilistic? In two novel tasks, children viewed the eye colors of animal parents and judged (phenotypic judgement task) and selected (offspring selection task) possible phenotypes of offspring. Across three studies (N = 353) with predominantly White U.S. participants, 4- to 12-year-old children showed a probabilistic understanding of genetic inheritance, and they accepted and expected variability in the genetic inheritance of eye color. Children did not show biases identified in prior literature (i.e., mother bias) but they did show two novel biases: perceptual similarity and sex-matching. These results held for familiar and unfamiliar animals and persisted after a lesson, suggesting children use a biased probabilistic model to think broadly about genetic inheritance.