According to the American Indian and Alaska Native Genetics Research Center of the National Congress of American Indians, DNA testing reveals the genetic similarities between people. This allows a DNA test to be used to determine which ancestral tribes a person may be related to, showing the probability of relation as a percentage.
To make the identification, a sample is taken from an individual. Samples can be hair follicles, spit, a swab of the cheek or blood. The sample is used to test for genetic markers that appear in various ancestral tribes. The greater the number of similar markers, the more likely the individual is to be a descendant of that tribal group. The testing cannot work as incontrovertible truth, however, as the markers are not unique to a single tribe or group. The greater number of people tested from a specific group, the better the chance of making a positive identification of a new individual with that group. Identifying as part of a group genetically can be used for more than genealogy purposes. The testing can also help to determine if an individual enjoys certain rights granted to existing tribal groups, or it can give forewarning to an individual of certain genetic diseases common to the group.