Genealogy –Discover Family Ancestry with DNA

Genealogy answers are not always easy to find and many people are turning to DNA testing.  There are some things you need to know before proceeding down that road.  The tests results for males and females are totally different.

For the female, mtDNA tests - Mitochondrial DNA (mtDNA) is contained in the cytoplasm of the cell, rather than the nucleus. This type of DNA is passed by a mother to both male and female offspring without any mixing, so your mtDNA is the same as your mother's mtDNA, which is the same as her mother's mtDNA.  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.

Y Line Tests - More recently, the Y chromosome in the nuclear DNA is being used to establish family lines. The Y chromosomal DNA test (usually referred to as Y DNA or Y-Line DNA) is only available for males, since the Y chromosome is only passed down the male line from father to son. 

Tiny chemical markers on the Y chromosome create a distinctive pattern, known as a haplotype, which distinguishes one male lineage from another. Shared markers can indicate relatedness between two men, though not the exact degree of the relationship. Y chromosome testing is most often used by individuals with the same last name to learn if they share a common ancestor.  This narrows the DNA testing down to just one of our 46 chromosomes, the male Y chromosome. 

All of our chromosomes, including the Y chromosome, consist of a few genes (about 2-3% of our DNA) with vast amounts of filler DNA (about 97-98% of our DNA) in between the genes. This filler DNA is also known as junk DNA and has no known function. So, along with the genes on the Y chromosome which a boy inherits from his father also comes this filler DNA being passed down virtually unchanged from generation to generation. Within these filler regions are certain known locations (loci)) where a short segment of DNA will repeat itself a number of times. This is known as a Short Tandem Repeat (STR) and its location is called a Marker. This is what makes testing of the Y chromosome (Y-DNA testing) useful in researching the direct paternal line and tracing surname lineages and why it is the type of DNA testing is being used.

Since Y-chromosome DNA is found only within the all-male patrilineal line and mtDNA only provides matches to the all-female matrilineal line, DNA testing is only applicable to lines going back through two of our eight great-grandparents - our father's paternal grandfather and our mother's maternal grandmother.

DNA tests can be used by genealogists to:

• Link specific individuals - e.g. test to see whether you and a person you think may be a cousin descend from a common ancestor

• Prove or disprove the ancestry of people sharing the same last name - e.g. test to see if males carrying the CRISP surname are related to each other

• Map the genetic origins of large population groups - e.g. test to see whether you have European or African American ancestry

Most DNA tests are done with a dna testing kit at home with a quick cheek swab which is then mailed to a laboratory, and it will take a month or two for results. These test cost anywhere from $100-$400. The more expensive tests are much more detailed than the cheaper test which gives you a better chance at locating relatives. The test for the female is cheaper but you really don’t get very much detail on your maternal line.

The male test is compared to all other Y chromosome tests. This really works best if you happen to have a name that has a large database and many people with that last name send their sample to that database.

In our case, my mother’s maiden name was Sprague and through genealogy we actually met cousins that we didn’t know existed even though they were my mother’s second cousins. There is a large Sprague database and the only male Sprague still living that we are aware of sent his sample to the Sprague database. We then got a result that was extremely close to our line and several that we would be related to a few generations ago and they keep coming in as more people get tested.

This was exciting news as we had been stuck on a Sprague born in 1794, to locate his father. We now knew for sure that we were related to one particular line that arrived in America in the early 1600’s. If you don’t have that type of database situation, there are many sites that handle these test results with Ancestry.com being one of the larger ones, but there is also Family Tree and numerous other sites.

Now as to the test for the female, we decided we would send my mother’s DNA to Ancestry.com.  We got about a 4 or 5 page report.  It essentially stated that about 30,000 years ago we had family in Asia and about 10,000 years ago we have family in Europe, but she descended from the Colonist.  Well, we already knew that!  Maybe some females have luck particularly if there family didn’t come to America at such an early time but needless to say it was a disappointment to us.

I think the DNA studies are fascinating and they have helped many a genealogist that was at a dead-end  It would be nice if they could perfect the female test some day but the male test is definitely worthwhile if you are looking for answers.. 

The copyright to this article is owned by Pamela Oglesby. Permission to republish this article in print or online must be granted by the author in writing.