Is Biology Destiny? A Sociological Explanation for Divergent Destinies

Abstract

Differential parental treatment has important implications for stratification research if human capital investments in children are differentially allocated according to child attributes that determine later attainment outcomes, such as ability, health or temperament. In this study, I ask, do parental investments in their children compensate for or reinforce birth endowment differences among children? Does the degree and direction of differential treatment—in terms of how parental time is allocated among children—vary across socioeconomics status? I use time diary data from the PSID-CDS to examine how total quantity of parental time, as well as type of parental time, is distributed among children. Birth weight is used to measure children’s birth endowments. Family-level fixed effects are used to account for shared unobserved characteristics among siblings (i.e. 756 sibling pairs, age 0-12). Findings demonstrate that the direction and degree of differential treatment—both in terms of the total quantity and quantity of development time spent with parents—varies by parent’s socioeconomic resources. Lower income and less educated parents reinforce endowment differences by spending more time with normal weight children (≥ 2500g). More advantaged parents compensate for differences by spending more time with low birth weight children. The findings are important for several reasons. First, the paper shows that sibling correlation studies underestimate the influence of family background in disadvantaged families because, in such families, family background increases, rather than decreases, sibling resemblance over time. In this case, family background exerts its influence in unexpected ways: producing diverging rather than converging destinies among siblings. Second, the study shows that the lasting effects of low birth weight are not
purely due to biological destiny but to biosocial interactions that both compensate for and reinforce early-life disadvantages.