Mitochondrial DNA -- it sounds scary. But it is really just a DNA sequence which can be used to trace the female lines in your family tree - your mother, her mother, your mother's mother, and so on. Mitochondria DNA, mtDNA for short, is found in both males and females, and is inherited from your mother. Only females pass on mtDNA to their children, but males do inherit it from their mother, even if they can't pass it on.

Much less commonly used than the more traditional Y chromosome testing, mtDNA tests are a helpful genealogy research tool because they can be used by both males and females. Because males cannot pass mtDNA on to their offspring, however, the only line this test follows is the mother's maternal line. Also, because mtDNA changes very slowly, it cannot determine close relationships as well as it can determine general relatedness. If two people have an exact match in their mtDNA, then there is a very good chance they share a common maternal ancestor, but it is hard to determine if this is a recent ancestor or one who lived hundreds of years ago.

If you're considering an mtDNA test, Family Tree DNA is running a special promotion during the month of October with large discounts on mtDNA tests and packages.