Studying the impact of race and ethnicity on epigenetic differences related to disease may shed light on the biological pathways through which environments contribute to health disparities. We recommend that all research clearly specify race and ethnicity as social categories and specify whether the focus of the study is on effects of self-identified or externally-identified race and ethnicity or, instead, on effects of continental ancestry or genetics. We demonstrate that due to the high levels of collinearity between self-identified race and continental ancestry, epigenetic studies focused on understanding the impacts of race and ethnicity should not statistically control for continental ancestry. Studies of the environment should control for self-identified race and ethnicity while studies of genetic impacts on epigenetic markers should control for continental ancestry as the most important confounders. Without a clear theoretical premise, quantitative studies of race and ethnicity and epigenomic regulation of disease will likely confuse the influences of continental ancestry and the environment on racial and ethnic differences in epigenetic markers.
Nutritional Epigenomics, 2019, Pages 51-65,