Advances in genomic technology have put the utility of collecting racial and ethnic data into question. Some researchers are optimistic about the potential of moving toward "personalized medicine" by using a person's genome to administer medications. Genetics will not erase the importance of race and ethnicity because race and ethnicity do not measure genetic composition. Unlike genes, race and ethnicity are social constructs; 2 persons with identical genetic makeup may self-identify as being of different race or ethnic origin. Race and ethnic categories have been subject to change over time; a person's self-identification may vary according to the context, wording, and format of the question asked. Despite the fluid nature of the concept, self-identified race and ethnicity can capture something that genes cannot, namely, aspects of culture, behavior, diet, environment, and features of social status that commonly used measures of socioeconomic status, such as income, education, and occupation, cannot measure.