Using nature to understand nurture

Abstract

Parents transmit advantages and disadvantages to their children, perpetuating inequalities in health, wealth, and well-being across generations (1). Disentangling the roles that nature and nurture play in intergenerational transmission is one of the most enduring and difficult problems in social science and medicine. On page 424 of this issue, Kong and colleagues use genetic data from trios of parents and offspring to address this challenge in a novel, intriguing way. They show that parents' non-transmitted genetic alleles (i.e., the part of the parental genotype the children didn't inherit) can nonetheless predict children's educational attainment. They call this effect "genetic nurture"-a indirect link between parental genotypes and children's characteristics that is not caused by the children's own biology, but is rather caused by the family environment provided by the parents (which was, in part, inherited from their parents, et cetera, back through a lineage). In contrast to results for educational attainment, parental alleles associated with height and BMI predict their children's bodies only insofar as the children actually inherit those genes. These results are consistent with twin studies, which also find evidence for moderate family environmental effects on educational attainment (2) but not height or BMI (3, 4). Kong et al.'s ingenious analysis of family data reminds us, yet again, of the methodological problems that plague social scientists as we try to understand individual differences in complex human behavior, but also illustrates how understanding nature can provide us with new tools for studying nurture.