Prepared by Elisabeth Lindsay.
A DNA marker is a gene or DNA sequence along a strand of DNA, and there are many markers, each with their own distinct location and code. Certain DNA tests evaluate and compare these markers to determine relationships among individuals and groups. DNA tests are often distinguished and priced by the number of genetic markers tested. According to FamilyTreeDNA a genetic testing company, the number of markers that should be tested depends on the objectives of the individual, and tests can be "upgraded" at any time to test a greater number of markers. Those considering DNA tests should carefully examine the options and the benefits of each test. For more information on DNA studies and their use in genealogy, see the GenWeekly articles, Beyond the Paper Trail: Discovering Family History with Different DNA Tests ($) and SNPs and Snails: What is your deep ancestry? ($).