What Money Can (and Can't) Buy: A Behavior Genetic Analysis of the Physical and Mental Health Benefits of Socioeconomic Advantage in Modern America

Socioeconomic status (SES) has long been observed to predict health and psychosocial functioning: The wealthy tend to be happier, healthier, and live longer than their poorer counterparts. Using contemporary samples of adolescent and adult American twin pairs raised in the same household (the National Longitudinal Study of Adolescent Health and the Washington State Twin Registry), this dissertation takes two approaches to investigating the SES–health gradient. First, individual- and family-level socioeconomic indicators (e.g., income, educational attainment, family income during childhood) as well as community-level measures of socioeconomic advantage or inequality (e.g., Area Deprivation Index, Gini Index) were used to systematically evaluate the effect of SES—controlling for genetic confounds that often lead to biased or spurious findings—on mean levels of mental and physical health and health behaviors. Second, the influence of SES indicators on genetic and environmental risk for the same range of health outcomes was evaluated to understand whether SES makes some individuals more or less susceptible to expressing a particular health phenotype. We hypothesized that the SES–health gradient is largely an artifact of gene-environment correlation, and the data decisively supported this prediction. We also hypothesized that genetic diathesis for negative health outcomes or behaviors would be greatest in the least advantaged environments. Instead, we observed that environmental risk for poor health is exacerbated by socioeconomic deprivation. Our results suggest that in 21st century America, money does not buy better health and well-being at the population level. On the other hand, reducing the socioeconomic burden of those at the lowest tier of the socioeconomic spectrum will yield better health for those at greatest environmental risk for poor health.