Biogeographical DNA

I have now had an opportunity to compare biogeographical DNA results from two different companies – AncestryDNA and 23andMe. (As explained in an earlier post, biogeographical DNA ancestry is based on the idea that after humans began to migrate out of Africa, population groups who lived in different regions of the world over time developed distinct genetic markers. Admixtures of these markers result when human populations mix, which has happened throughout human history. Tests for specific genetic markers can reveal broad population groups that make up a person’s ancestry.)

According to AncestryDNA, I am roughly:

European 94%
Sub-Saharan African  6%
East Asian  0%
Native American  0%

According to 23andMe, I am roughly:

European 99%
Sub-Saharan African  0%
East Asian, Native American  0.2%
Middle Eastern, North African  0.1%

OK, I already knew that I’m overwhelmingly of European descent, and both tests agree. When I had the AncestryDNA test done several years, ago, it did not break out sub-groups among Europeans at that time. 23andMe does that, at three confidence levels: conservative, standard, and speculative. Here’s a rendering of my results at the speculative level:

23andMe results, exampleThe display tool is quite interesting. Viewers can click on each of the population groups to find out more about how that group is defined and what migrational movements might affect it, as well as the size of the sample in the company’s database.

The results fit what I know of my own ancestry only roughly. They under-count German ancestry. Everyone on my father’s side was of German descent, although I have precious few records from before they emigrated from German states in the 1800s. The results over-count British ancestry. I know that some of my mother’s ancestors were of British and Scots Irish decent; some were of Swiss and French descent. But I also know that migrations of peoples within Europe over centuries may well produce mixtures that are not exactly coterminous with countries of emigration during the 1700s and 1800s. And of course, borders between countries, including who is occupying whom, change over time.

What does it mean that the results differ regarding a bit of non-European ancestry? I had grown up hearing that we have Cherokee ancestry, which was initially what led me to DNA testing, since I could not locate any Native Americans in my family history research. The possibility of sub-Saharan ancestry led me to exploring strategies light-skinned African Americans used to pass as White during the time of Jim Crow. While the results from 23andMe to not entirely preclude some non-European ancestry, they conflict with results from AncestryDNA.

What I have learned is that results of different companies differ. Your Genetic Genealogist (who consults for Finding your Roots with Henry Louis Gates, and Genealogy Roadshow) compared his own results across four companies: AncestryDNA, 23andMe, Genio2.0, and Family Tree DNA, using what he already knew from extensive family history research. None of the four companies reported exactly the same results. They all agreed that he is mainly of European descent, but differed on the broad ethnic breakdowns within Europe. One reason the author gives for the differing results is that companies do not all define admixtures in exactly the same way. While some use more recent population locations, others draw more on distant past locations and migrations. Consider, for example, from the distant past Genghis Khan’s Mongol empire that went as far west as present-day Germany.

Another factor is exactly who (and how many people) are in the company’s reference database, and which population groups are not well-represented. The main company Your Genetic Genealogist does not have confidence in is AncestryDNA.

A different comparison is reported on the DNA Explained blogsite, under the entry: Ethnicity Results True or Not? Based on comparing results and examining four companies (AncestryDNA, 23andMe, Family Tree DNA, and the Genographic Project), the writer regards Family Tree DNA as most trustworthy:

Unlike the Genographic Project, Family Tree DNA doesn’t have a large nonprofit behind them.  Unlike 23andMe, they are not subsidized by the medical community and venture capital.  And unlike Ancestry.com, Family Tree DNA is not interested in selling you a subscription.  In fact, the DNA market could dry up and go away for any of those three, meaning 23andMe, National Geographic and Ancestry, and their business would simply continue with their other products.  To them, DNA testing is only a blip on a spreadsheet.  Not true for Family Tree DNA.  Their business IS genetic genealogy and DNA testing.  So of all these vendors, they can least afford to have upset clients and are therefore the most likely to be the most vigilant about the accuracy of their testing, the quality of the tools and results provided to customers.

Yet another helpful resource for consumers who wish to compare DNA and other family history resources is the DNA Testing and Ancestry Guide from Consumer Affairs.

Charmaine Royal of the Duke Institute for Genome Sciences and Policy sums up biogeographical DNA as an inexact science that has the significant limitation of reifying the inaccurate notion that there are identifiable and distinct races. She explains:

There’s this perspective that genetics provides the truth, and that may need to be challenged. In general, genetic ancestry testing is fallible just like many of the tools we use. Some people think that genetics will provide the be all and end all of information about their ancestry. There are limitations as to what ancestry can provide.

So what do I recommend to readers? My main recommendation is to use multiple sources and tools to figure out your family history. DNA testing is a useful and interesting tool, but it is not infallible, and it does not replace engaging in the work of using the various archival databases and other sources discussed throughout this blogsite. Best DNA Test for Ancestry can help you do some comparison shopping.

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