Genetic mechanisms in the intergenerational transmission of health.

This paper uses a sample of adoptees to study the genetic mechanisms underlying intergenerational associations in chronic health conditions. I begin by estimating baseline intergenerational models with a sample of approximately 125,000 parent-child pairs, and find that children with a parent who has a specific chronic health condition are at least 100% more likely to have the same condition themselves. To assess the role of genetic mechanisms in generating these strong correlations, I estimate models using a sample of approximately 2400 adoptees, and find that genetic transmission accounts for only 20-30% of the baseline associations. As falsification tests, I repeat this exercise using health measures with externally established levels of genetic determination (height and chicken pox), and the results suggest that comparisons of biological and adopted children are a valid method of isolating genetic effects in this sample. Finally, to corroborate these adoptee-based estimates, I examine health correlations among monozygotic twins, which provide an upper bound estimate of genetic influences, and find a similarly modest role for genetic transmission. I conclude that intergenerational health transmission is an important hindrance to overall socioeconomic mobility, but that the majority of transmission occurs through environmental factors or gene-environment interactions, leaving scope for interventions to effectively mitigate health persistence.