In national statistics for the United States, it is common to see information about different segments of the population. For example, data from the U.S. Census and many national surveys on drug use often are subdivided in relation to four racial groups: (1) white, (2) black, (3) Asian or Pacific Islander, (4) American Indian or Alaska native. In concept, "racial heritage" refers to biologically inherited origins, but most people appreciate that these categories of race are determined more by social ideas and customs than by sharp genetic distinctions among these four groups. Some people even change their racial affiliation as they change their social perceptions.

In some national statistics and survey data, it also is common to see subdivisions in relation to "ethnic heritage," which sometimes refers to a person's country of origin but more generally refers to shared social and cultural characteristics. For example, people with...