More on DNA ancestry testing- a personal reflection

Readers may have already seen my two previous posts on misconceptions of DNA ancestry tests. This was compiled based on experiences of other people who have done these tests. However, now three generations of my own family have done DNA ancestry tests and the results were very interesting.

I think the main point of interest were the false results. I’m not talking about the usual strange results from trace regions, but in our case in major regions of ancestry. For a quick background, my parents each are 99% from a single population group making me a 50-50 mix of those two groups. My spouse also is originated from two population groups but she is a 75-25 mix.

The biggest shock was that my spouse’s test came back with a result of 26% Italian. Now one problem is that my spouse comes from a reference population which I’m sure has a small data set. We have done a genealogical tree along with the DNA test and we are 99% positive it is a false result. And in the unlikely event that one of my spouse’s ancestors who we know the least about could be Italian, it would only make her 12.5% Italian. It was just a surprise that a major region of ancestry came up wrong.

If we look at my daughter’s test, she also had some surprising findings. To reiterate, she is basically originating from four different population groups. However one group, Asia Minor, was calculated to be 22% whereas her mother only had 12% and based on the genealogical calculation should have had 25% meaning my daughter should have had only 12.5%. It makes no sense how that percentage would increase from mother to daughter and as mentioned, with the genealogical tree, we are quite confident in estimating the amount of that region’s DNA that both should have. She also got some really whacky results in the minor and trace regions which also made me question the test especially as no one else in the family had those regions- 5% Iberian Peninsula doesn’t just come from nowhere! As we got her results before my mother’s, we were getting pretty excited that her result would reveal some family secrets, but that wasn’t the case.

I got the sense that the data was changing a lot because when I compared the breakdown of DNA in the reference populations (most similar DNA) assigned to my family members with that on the website list of those populations, every group was different. From a statistical standpoint, the DNA of at least millions of more people would have to be collected to get closer to some kind of statistical significance. The company we used has under a million people tested at the time of writing.

So in conclusion, we got some pretty incorrect results for our family’s DNA ancestry testing. Seeing all those results that were not correct, in some cases very wrong, makes me wonder how reliable any of the results are. Maybe my mother’s family history is more interesting than we think. Either way this highlights the shortcomings and limitations of DNA ancestry tests as well as the importance to conduct genealogical research as well to triangulate the data from DNA tests.


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