Is Biology Destiny? Birth Weight and Differential Parental Treatment

Amy Hsin, University of Michigan

Time diaries and sibling fixed effects models are used to examine whether parental time investments in children compensate for or reinforce birth weight differences among siblings (i.e. 666 sibling pairs, age 0-12). The findings demonstrate that the direction and degree of differential treatment varies by socioeconomic status (SES). Less advantaged parents reinforce differences by spending more time with normal-weight children. Advantaged parents compensate by spending more time with low-weight children. First, the findings show that the lasting effects of low birth weight may not be entirely due to biology; biosocial interactions both compensate for and reinforce early-life disadvantages. Second, sibling correlation studies may underestimate the influence of family background in determining status attainment because disadvantaged families act in ways that decrease sibling resemblance over time. In low-SES families, shared family background exerts its influence in unexpected ways: producing diverging rather than converging destinies.