Decomposing the causes of the socioeconomic status-health gradient with biometrical modeling

The consistent relationship between socioeconomic status (SES) and health has been widely covered in the media and scientific journals, which typically argue that physical-health inequalities are caused by material disadvantage directly or indirectly (e.g., chronic environmental-stress, health care resources, etc.). Such explanations do not explain the finely stratified health differences across the entire range of SES. Recent theories have helped address such limitations, but implicate multiple different explanatory pathways. For example, differential epidemiology articles have argued that individual differences are the "fundamental cause" of the gradient (Gottfredson, 2004). Alternatively, variants of allostatic load theory (McEwen & Stellar, 1993), such as the Risky Families model (Repetti, Taylor, & Seeman, 2002) implicate the early home-environment. These theory-driven pathways align with interpretations associated with biometrical models; yet, little research has applied biometrical modeling to understanding the sources of the gradient. Our study presents several innovations and new research findings. First, we use kinship information from a large national family dataset, the NLSY79, whose respondents are approximately representative of United States adolescents in 1979. Second, we present the first biometrical analysis of the relationships between SES and health that uses an overall SES measure. Third, we separate physical and mental health, using excellent measurement of each construct. Fourth, we use a bivariate biometrical model to study overlap between health and SES. Results suggest divergent findings for physical and mental health. Biometrical models indicate a primarily genetic etiology for the link between SES and physical health, and a primarily environmental etiology for the link between SES and mental health. (PsycINFO Database Record (c) 2019 APA, all rights reserved).