racial and ethnic clustering in residential settings. In the general US population, Blacks, on average, have lower education levels than Whites, with 14.3% of Blacks reporting a bachelor’s degree, compared with 26% among Whites (US Census Bureau, Census 2000 Brief, 2003). In less affluent urban areas, populated predominantly by Blacks and other ethnic minorities, residents tend to have lower levels of education, compared with those who live in more ethnically integrated neighborhoods, where their concentrations are lower. If more educated Blacks are the ones who are more inclined to participate in genetic research, then it is probable that recruitment would be more difficult as the more educated residents are more sparsely distributed in a given location.
