Many people are taking genealogical DNA tests these days. While that sounds great, the sad part is that many, and I would say most, aren't interested in connecting with their distant cousins to help find their genealogical information. Instead, as a result of the advertising Ancestry DNA puts out, they are only interested in their ethnicity. In my opinion, this ethnicity estimate is about the least valuable piece of information you get from your DNA test. Here is a demonstration of this.
First, from their known genealogically researched ancestry, my mother and her siblings are 100% German. You also need to understand that Germany contains several ethnicities by itself. If you just consider the population in the northeast being more closely related to the Dutch, the population to the southwest more closely related to the French, then those to the east more Bohemian or other eastern Europe. Then, you need to figure in the large amount of migration and invasion that occurred between the German and French areas, the British Isles and Scandinavia. The idea that they'd show up as "German" is a stretch.
Previously, I had my mother and her sister have their DNA test done. Now, I just got the DNA test results back for another of my mother's sisters. Here are their ethnicity estimates:
66% West and Central Europe
19% Southeast Europe
15% British Isles
Aunt # 1:
76% West and Central Europe
14% British Isles
7% Southeast Europe
South Central Africa
Aunt # 2:
98% West and Central Europe
With Family Tree DNA, which is the company that performed these tests, West and Central Europe can be considered French, German, Dutch, Belgian and surrounding areas. Given the numbers shown above, if we average them, I believe it's safe to say that their parents, in combination, are safely at least 75% pure German. Two of the sisters test as 15-19% British Isles and the other shows no British Isles whatsoever. Could this mean that my second aunt that tested just didn't inherit any of the DNA that shows up as British Isles? I tend to believe that given population base that was tested, we are seeing some of the migration/invasion discussed previously and the test just didn't calculate that ethnicity for my second aunt. I'm sure a part of it is different segments of DNA inherited but I believe it's just in the calculation. The same thing can be said for the southeast Europe result with a part of that also potentially being the Jewish portion being calculated in a different way. The results for my first aunt initially showed up as about 10% Ashkenazi Jew. I tend to believe that the Shephardic Jew and the southeast Europe are what was initially calculated as Jewish. Then the trace amounts really can mean nothing. It can just be small pieces randomly matching that found in the ethnicities showing up as a trace.
Regardless of what their "real" ethnicity is, the point I wanted to illustrate with this post is that the three sisters, which Family Tree DNA confirms are full sisters, the daughters of the same mother and same father, show drastically different ethnicities. Getting a DNA test to find out your ethnicity is not providing what many people believe it does.