Heritability of education rises with intergenerational mobility

Per Engzell and Felix C. Tropf - PNAS December 17, 2019 116 (51): 25386-25388

Figure: Genetic and environmental influences on educational attainment. (A) Trends in intergenerational mobility across 10 countries: Australia (AUS), Denmark (DNK), Finland (FIN), Germany (DEU), Italy (ITA), Norway (NOR), Spain (ESP), Sweden (SWE), United Kingdom (GBR), and United States (USA). (B and C) Association of intergenerational mobility with heritability (h2h2) and shared environmental influences (c2c2). Superimposed lines show the least-squares line of best fit, with 95% confidence intervals indicated by shaded areas; marker labels encode the country and decade of birth for each cohort.

As an indicator of educational opportunity, social scientists have studied intergenerational mobility—the degree to which children’s attainment depends on that of their parents—and how it varies across place or time. We combine this research with behavior genetics to show that societal variation in mobility is rooted in family advantages that siblings share over and above genetic transmission. In societies with high intergenerational mobility, less variance in educational attainment is attributable to the shared sibling environment. Variance due to genetic factors is largely constant, but its share as a part of total variance, heritability, rises with mobility. Our results suggest that environmental differences underlie variation in intergenerational mobility, and that there is no tension between egalitarian policies and the realization of individual genetic potential.

Intergenerational education mobility—how strongly educational attainment persists from parent to child—is commonly used to indicate societies’ degree of openness or equality of opportunity (1, 2). A limitation of this literature is that it often is silent on the channels of transmission. Yet, we may view genetic transmission differently from other advantages such as parents’ ability to pay for good neighborhoods, schools, or access to college (3, 4). Insofar as genetic factors capture relevant abilities, their influence is consistent with meritocratic norms (5⇓–7). Such norms can be motivated on grounds of efficiency, as a society’s viability depends on its ability to attract competent leaders and innovators (8, 9).

In other words, it matters not only whether education is inherited, but also how (3). One approach to the “how” question comes from behavior genetics (10). By comparing outcomes for family members with varying degree of genetic resemblance—typically, twins—we can partition variance in an outcome to that attributable to genetic factors (heritability, h2h2), shared sibling environment (c2c2), and idiosyncratic factors (e2e2) (11). While such studies potentially tell us much about the distribution of opportunities, societal comparison has rarely been central to them. In this study, we ask: Where intergenerational mobility is higher, does the balance of “nature” and “nurture” in educational attainment differ?

See more: https://www.pnas.org/content/116/51/25386