Is Resource Dilution a Law? Sibship Size and Educational Outcomes Across Time and Group.

One of the most consistent patterns in the social sciences is the relationship between sibship size and educational outcomes: those with fewer siblings outperform those with many. The most prominent explanation for this pattern is resource dilution--parents' resources are finite and spread more thinly as the number of children in the family increases. This theoretical claim is provocative because it transcends place and time, suggesting a universal law. Studies beyond the United States, however, indicate another possibility--that the relationship between sibship size and educational outcomes may depend on context. With a focus on historical and contextual patterns in the U.S. setting, we extend tests of the dilution model in two ways with data from the General Social Surveys 1972-2010. First, we find that the effect of sibship size on educational outcomes has slowly declined during the twentieth century, but has also shown signs of uptick among the most recent cohorts, a pattern that resembles the broader patterns of inequality exhibited in Kuznets Curve. Second, large sibships are less detrimental among individuals that identify as Mormon than for other religious groups, highlighting the way in which broader social norms influence the consequences of sibship size. [ABSTRACT FROM AUTHOR]