Genetic Genealogy

Getting started with DNA testing for genealogy is not any more difficult than searching the various records you have learned about as you have pursued your family history research.  A science background is not necessary.

There are two types of DNA tests available for genealogy: Y DNA Tests and mtDNA Tests.  The Y DNA test is more suitable for testing the male (surname) line, in a historical time frame because the Y chromosome typically follows surnames.

The Y DNA tests are only available for males, since this test involves testing a small portion of the Y chromosome, which is passed from father to son.  Males have both an X and a Y chromosome.  They receive the X chromosome from their mother, and the Y chromosome from their father.  Females have two X chromosomes, one each from their father and mother.

Testing Y DNA provides information about the direct male line, which would be the father, his father, his father, and so forth, back in time.  Scientists have discovered that a small portion of the Y chromosome is passed from father to son, virtually unchanged.  Therefore, if a father and son are tested, their results would usually match.  If two cousins are tested, who have the same grandfather, their results would match or be a close match.  By comparing the result from a Y DNA test of two males, you can determine if they are related and approximately when their common ancestor occurred.

The locations tested on the Y chromosome for the Y DNA test are called Markers.  (Each location is labeled with a number, i.e. DYS #393, DYS #390, DYS #19, etc.)  In the lab, the technician will count the number of repeats of the basic building blocks of DNA at each marker.  As you look at the spreadsheet at the “Test Results,” site on this website, the number you find under each Marker is the number of repeats found at that particular marker for that Participant.  (All the Blands seem to have 13 repeats at Marker #DYS393, for instance.)  Notice that we said father and son results would USUALLY match.  That is because mutations can crop up at any time–meaning the repeat count can change up or down by 1, (rarely more than 1).  So, there could, theoretically, be a mutation between a father and son.  That is why we urge you to select the oldest living male as the test subject.  His DNA would be a closer match to the generations before.