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Ethnicity reports are only estimates

Here’s a quiz for DNA Sunday:

How many people are represented by the DNA results shown below?

DNA Result #1:

Great Britain 49%
Scandinavia 31%
Europe East 4%
Italy/Greece 4%
Europe West 4%
Iberian Peninsula 3%
European Jewish 2%
Ireland 1%
Africa North 1%
West Asia: Caucasus 1%

DNA Result #2:

West and Central Europe 87%
Scandinavia 11%
West Middle East 2%

DNA Result #3:

British & Irish 38.0%
French & German 27.1%
Scandinavian 4.2%
Broadly Northwestern European 24.2%
Southern European 1.4%
Eastern European 0.8%
Broadly European 4.1%
West African 0.2%

DNA Result #4:

Northwest European 66%
Mediterranean Islander 18%
Northeast European 12%
Southwestern European 4%

DNA Result #5:

Northern European 41%
Mediterranean 38%
Southwest Asian 21%

DNA Result #6:

North Sea 28.92%
Atlantic 29.51%
Baltic 11.42%
Eastern European 10.91%
West Mediterranean 8.07%
West Asian 5.5%
East Mediterranean 2.59%
Red Sea 1.65%
South Asian 0.64%
Northeast African 0.79%

DNA Result #7:

East European 12.97%
West European 49.33%
Mediterranean 23.65%
West Asian 10.75%
Northeast Asian 0.31%
Southeast Asian 0.11%
Southwest Asian 2.21%
African 0.65%

If you guessed that all of these results are for the same person — namely, The Legal Genealogist — give yourself a gold star.

The results, of course, are from different companies or services.

DNA Result #1 shows my current ethnicity estimate from AncestryDNA. DNA Result #2 is from Family Tree DNA. DNA Result #3 is from 23andMe. DNA Result #4 is from DNA.Land, and DNA Result #5 from National Geographic’s Geno 2.0 Project.

The last two both come from admixture calculators at GedMatch.com, with DNA Result #6 from the Eurogenes EUtest V2 K15 calculator and #7 from the Dodecad V3 calculator.

There have always been differences between the companies.1 But the differences aren’t getting any better over time; if anything, they’re getting worse.

Some of the differences, of course, are because of the different ways geographic areas are lumped together. At DNA.Land, for example, Northwest European includes “… Icelandic in Iceland; Norwegian in Norway and Orcadian in Orkney Islands.” That’s likely showing up as Scandinavian at AncestryDNA.

But the big reason why there are differences is because of what these admixture tests do: they take the DNA of living people — us, the test takers — and they compare it to the DNA of other living people — people whose parents and grandparents and, sometimes, even great grandparents all come from one geographic area. Then they try to extrapolate backwards into time. Nobody is out there running around, digging up 500- or 1,000-year-old bones, extracting DNA for us to compare our own DNA to.

So coming up with these percentages in these tests requires this fundamental assumption: that the DNA of the reference populations — those groups whose parents, grandparents, great grandparents and more all come from the same area — is likely to reflect what we might see if we could test the DNA of people who lived in that area hundreds and thousands of years ago.

In other words, these percentages are:

• estimates,

• estimates based on comparisons not to actual historical populations but rather to small groups of people living today, and

• estimates based purely on the statistical odds that those small groups tell us something meaningful about past populations.

These limitations are true of all of the testing companies. You can see from the above that my own results are — literally and figuratively — all over the map. I’m German with some companies, not German at all with another. Largely Scandinavian with one, only slightly Scandinavian with the others. A recent change in analysis at one company found my Germans, but in the process lost my British.

DNA testing for genealogical purposes is a wonderful tool. But people get disappointed when they see these percentages and they don’t match up to their own paper trail and don’t match up from company to company. And when they get disappointed, they may lose interest in genealogy or in DNA testing. And when they lose interest, we lose out on the paper trail information they might add to our mix.

The bottom line remains: We need to educate our friends and our families, our DNA cousins, to the limits of what these percentages can show — and to show them all the other things DNA testing really can help with.

Because it’s still not soup yet.2

And because we aren’t about to go digging up those old bones, it may never be soup.


SOURCES

  1. See e.g. Judy G. Russell, “Admixture: not soup yet,” The Legal Genealogist, posted 18 May 2014 (http://www.legalgenealogist.com/blog : accessed 15 Apr 2017). Also, ibid., “Making the best of what’s not so good,” posted 22 Feb 2015, and “Those percentages, if you must,” posted 14 Aug 2016.
  2. For those too young to remember the reference, the Lipton Soup Company had a string of ads in the late 1960s and early 1970s. The mother in the ad would begin preparing Lipton soup, a child would ask, over and over, “is it soup yet?” and the mother would answer “not yet” over and over until finally she’d say, “It’s soup!” So “not soup yet” means “not finished” or “not ready.”
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