It is widely accepted among social scientists that both nature and nurture determine individuals’ future health and socioeconomic outcomes. From the empirical perspective, however, disentangling the role played by nature and nurture (as well as their potential interactions) is not straightforward. We take advantage of recent advances in molecular biology to study how individuals’ genetic propensity to obesity (as measured by BMI polygenic scores derived from genome-wide association studies) as well as different measures of their environment determine their obesity status at an elderly age in the United States. In particular, we consider two environmental measures: individuals’ socioeconomic status during childhood, and the cohort they belong to (as the time trend in obesity in the US displays important changes in the obesogenic environment), neither of which can be possibly affected by their obesity status later on in life. Since individual genetic heterogeneity associated with adiposity may as well influence behavioral responses to environmental differences, we also study whether and how such differences exacerbate or mitigate the effects of individuals’ genetic inheritance.