Household Instability and Sibling Similarity in United States

• In Event: Family Section Roundtables
  In Refereed Roundtable (60 minute): Table 9: Family Structure and Change

Abstract

This study investigates how family instability and family structure shape developmental similarity among siblings in the United States. Although siblings share genetic backgrounds and aspects of a common environment, their educational attainment, health, and socioeconomic outcomes frequently diverge. Moving beyond explanations centered solely on individual differences, this research draws on family systems theory and life course perspectives to examine the degree to which siblings resemble one another as a reflection of family-level processes. In doing so, it also situates family structure within broader systems of social stratification, recognizing that structural forces such as inequality and racialized disadvantage shape family formation and stability.

Using nationally representative longitudinal data from the National Longitudinal Study of Adolescent to Adult Health (Add Health), the study assesses sibling similarity across income, educational attainment, self-rated health, and chronic disease status. Family structure is categorized as two-continuous marriage, single-parent, or reconstituted families, and instability is measured by the number of changes in parental residential and romantic partnerships from birth through adolescence. Intraclass correlation coefficients and multilevel linear models are employed to evaluate within-family resemblance and to test whether family structure and instability predict variation in sibling similarity, controlling for demographic and parental background characteristics.

The preliminary findings suggest that more stable and resource-equitable family structures enhance the developmental similarity of siblings into adulthood. Conversely, family disruption or reconstitution may weaken the “equalizing effect” of the family environment, making individual development more contingent on external conditions and chance circumstances.

Author

• Aitong Li, University of Florida