Is Biology Destiny? The Coherence of Children’s Beliefs About Physical and Psychological Traits

In adults, biological causes are commonly associated with immutability, a correlation observed in various contexts, including risky behavior and mental disorders. However, it remains unclear when during their development children coherently connect these ideas in relation to reasoning about physical and mental traits and whether they reason differently by domain. Understanding this is relevant to illuminating children’s theoretical conceptions about the body versus the mind. It can also clarify the extent to which children may fall prey to potentially deleterious assumptions that mental capacities are not only heritable but fixed. Prior work has suggested that a more sophisticated differentiated understanding of psychological traits may begin to emerge around 8-years of age. Building on this, in Study 1a we therefore examined U.S. third graders' reasoning about the inheritance and stability of physical and mental traits and whether their ideas coherently covary within each domain. In Study 1b, we further investigated the robustness of third graders' differentiated understanding of physical and mental traits by exploring whether participating in an early science curriculum that presented simplified information about physical traits affected children's thinking about mental traits. Taken together, results across the two studies reveal that third graders' display robust coherence in their reasoning about the inheritance and stability of traits. Children consistently judged physical traits as more likely to be inherited from parents and less malleable than mental traits, with children’s ideas about heritability and stability showing consistent connections within each domain. Moreover, exposure to early life science teaching about physical traits did not alter children’s perception that mental traits are more influenced by environmental factors, less inherited from parents, and more malleable. By 8- to 9-years of age, children therefore clearly distinguish body from mind in theoretically coherent ways. Nevertheless, the consistent covariance between beliefs about heritability and stability should provoke caution when talking to children about parent-child resemblances in capacities like intelligence lest children infer that their cognitive abilities can not be improved through effort.