A number of DNA tests can provide information about ethnicity. One is the Y-chromosome test, which, because it determines maleness, can be used only by sons and their fathers. Because a particular family's Y-chromosome undergoes small changes, or mutations, and is therefore unique, it can be traced back several hundred years through paternal lineage. Y-chromosome test results will demonstrate if you can likely be lumped into a particular haplogroup, or category of humans sharing similar DNA profiles. If a female wants to gather the same kind of information, she can seek enlist the participation of her father, her brother, her father's brother or her father's brother's son.
Another test for ethnicity is the mitochondrial DNA test. Mothers pass mtDNA on to their daughters and sons, so anyone can be tested. Like the Y-chromosome, MtDNA undergoes mutations over time, making it unique, therefore traceable back several generations to possible haplogroups.
A third test is autosomal DNA testing. An autosome is a chromosome that is not gender-determinate. People carry 22 pairs of autosomes in each cell along with the chromosome pairs that determine gender: X and Y for males and XX for females. Each part of an autosome pair comes from each parent, so autosomes can be tested to uncover your complete genetic makeup. Your results can then be compared to known haplogroups back several generations, and possible linkages suggested.
Thanks to a plethora of online genetic testing labs, ethnicity testing can be done at home, although some may direct you to an actual lab in your area for your DNA collection. A common technique is the use of buccal swabs, which collect saliva from the inside of your cheek.
Testing labs may not offer all types of ethnic genetic testing. Some may specialize in autosomal testing or testing for Native American ancestry. Time spent researching what you want to learn will help you narrow down the possibilities to a reasonable number of labs from which you can request information. Genetic testing services offer a menu of tests with a range of fees. Reliable results are best obtained from a member of the American Association of Blood Banks, which maintains high standards for its member labs.