Autosomal DNA is the most commonly used DNA test for genealogy. It has the advantage of potentially providing information on all branches of your genetic family tree, however, its utility diminishes after a few generations. You have a >90% probability of sharing DNA with third cousins, with whom you share great-great-grandparents, but the probability of sharing DNA decreases rapidly to less than about 10% between sixth cousins. Y-DNA and mitochondrial DNA (mtDNA), by contrast, only provide information on the direct paternal and maternal lines, respectively, but as there is no recombination, these types of DNA can provide information for many more generations.
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Autosomal, Y-DNA, or mtDNA?
