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Saturday, June 3, 2017

The Challenge of Interpreting My DNA Test Results

Most of the articles I have read and the explanations I have listened to about genealogical DNA testing have centered on complicated explanations of X-chromosome or autosomal DNA testing, Y-chromosome DNA testing, and mitochondrial DNA testing. I liken these explanations to telling me how my car's engine operates when I am buying a car. I may be interested in fuel injectors, torque, and other technical aspects of my car's operation, but all of that "under the hood" type explanation is superfluous when I start driving my car. I am not interested in becoming a mechanic (although I have been a pretty decent one over the years).

Likewise, when I get my DNA test results from the major DNA testing companies unless I investigate deeply into the "raw data" I never hear about the chromosomes or whatever. It is just like driving away in my new car. I know something is happening under the hood, but all I really care about is the way it drives.

What I do get from the DNA providers are some fancied up statistics with some generalized conclusions, just like what I usually get from a car salesman or an advertisement.

So now I have essentially three different sets of results from my two DNA tests: the explanation given to me by from their DNA test, the explanation given to me by from their test and now, the explanation given to me by from the raw data of my test. In addition, I have another way to look at my ancestry: the analysis by location from the Family Tree. Now that I think about it, I really have yet another DNA test result: the one from the older analysis before they applied their "upgrade."

From my standpoint, I may as well be driving five different cars. Here is what I can see. documented data in the Family Tree. My knowledge of the origin of my ancestors from extensively documented sources going back six or more generations tells me my ancestors came from the following:
  • America back to 1620, primarily New England on more than one line and then to England with the possibility of one ancestral line tracing back to The Netherlands before 1620. 
  • Denmark (i.e. Scandinavia) starting back about four generations on two lines
  • Two lines that go to Wales.
  • One line that goes to Northern Ireland and likely originated in Scotland.
  • One line that goes to Ireland. 
Here is the fan chart showing the places where my family originated.

OK, so what about the DNA tests? says I am primarily:
  • Great Britain (England, Scotland, Wales and perhaps Northern Ireland?) 55%
  • Scandinavia  29%
  • Iberian Peninsula 11%  
  • Ireland 5% 
I am not sure where the Iberian Peninsula came from, but if I look at it closely, I see that the range is from 2% (close if not in the margin of error) up to 19%. The main problem is the time depth. Given my researched results, any Iberian influence would have to come from ancestors that were more than six generations in the past.

Next, I have My original results before the "upgrade" had the following:
  • British and Irish 87%
  • Scandinavian 9.3%
  • Ashkenazi Jewish 2.5%
  • South Asia 1.2%
Well, there seems to be no question that most of my ancestors come from the British Isles. This also agrees quite well with my own research since one of my lines is arguably Jewish and another may be a Gypsy.

But what about the upgrade? Here are the results now.
  • English 74%
  • Irish, Scottish, and Welsh 14.2%
  • Italian 3.5%
  • Baltic 1%
  • West Asia 1.9%
Apparently, my Jewish heritage has disappeared and my ancestors now come from Italy, the Baltic and West Asia (which may still include my Gypy heritage). 

Then I uploaded my DNA test to and got the following results:
  • English 63.4%
  • Irish, Scottish, and Welsh 13.1%
  • Scandinavian 12.2%
  • Italian 11.3%
Given the vague geographic designations that could possibly contain any number of ethnic groups, this doesn't tell me much at all especially in light of my own documented research.

What is missing?

The answer to that is clear: I have no idea of the time depth we are talking about. Historically, my English ancestors could have come from Scandinavia, Central Europe or Italy since each of these areas sent armies into England and parts of the rest of Great Britain. Why did some percentages disappear and others appear? 

Stay tuned for more analysis in future posts. 


  1. If you don't mind me asking, how or where did you create the fan chart using locations?

    1. Oh, I;m sorry, I forgot to note that it came from's Consultant Planner on the Help Others menu from the Get Help link in the upper right hand corner of the startup page.

  2. Thanks. That is exactly what I needed.

  3. I was supposed to have ancestors ( Jewish )and that do not show up in my test. I,also,do not understand my Central América ancestry. Sincerely, Antonio Sanchez. Connecticut