In contemporary society, racial groups differ on a broad range of social, behavioral, nutritional, psychological, residential, occupational and other variables. And given that biology is not static but is adaptive to the environmental conditions in which the human organism exists, there are likely to be interactions between the social environment with both innate and acquired biological factors. Thus, although variation in gene frequency is unlikely to play a major role in accounting for racial disparities, differences in gene expression linked to the occupancy of different environmental contexts could play a critical role. Epigenetics refers to changes in gene expression that are not caused by changes in the nucleotide sequences of the DNA. Recent research reveals that exposure to risk factors and resources in the social environment can produce changes in gene expression (Williams et al. 2010). Future research on racial inequities in health needs to more systematically explore the extent to which the distinctive residential and occupational environments of racial minorities can give rise to patterns of social exposures that can produce epigenetic changes in gene expression and tissue and organ function (Kuzawa and Sweet 2009).
