And maybe never
The Legal Genealogist wants everyone who’s ever taken a DNA test that provides a set of ethnicity or admixture estimate percentages to repeat after me:
“It’s not soup yet.”1
And it may never be.
It’s a major step forward in our quest to gain information about our distant ancestors — where they lived, where they came from. It’s as good as it comes given the limits of science. It applies the very best of a set of statistical algorithms to what science knows to come up with a formula that tells us what it can about our origins.
And the very best of what it can tell us is still a guess.
Now you may be sitting there thinking, “but they don’t teach this in law school. How can she know?”
I know because I’ve spent a fortune testing relatives who’ve been kind enough to let me manage their results. And I can see what happens when, for example, you apply the very best of a set of statistical algorithms to what science knows to come up with a formula — and then apply that formula to people whose results should be pretty much identical.
People like my mother’s full blood siblings.
Four of them have tested. They all share the same mother, same father, so same grandparents and great grandparents on back into the mists of time. Their DNA establishes that fact beyond any question. No non-paternal events here, no undocumented adoptions.
So if all four have exactly the same parents, and grandparents, and great grandparents, and on back through the generations, they ought to have the same genetic admixture, right? Ethnically, looking back at their heritage 500 or 1,000 or 10,000 years ago, they can’t be different.
Except they are, at least according to this very best of statistical algorithms. Take a look at the chart below:
So… the population group labeled European Northlands “centers on the people of Scandinavia.”2 Does this family have any Scandinavian ancestry? Three of the four show traces, the fourth shows none at all.
Well, then, what about the North Circumpolar group — a group that “began around the arctic as hunter-gatherer peoples … (and) stretches from Lappland east to Greenland”? Three of the four show traces of that, the fourth shows none at all.
What about the North Mediterranean Basin population? A “distinct European cluster… situated in the southwest of Europe from Spain to Greece.”3 Three of the four show traces of this group, the fourth shows none at all.
We might be tempted to say yes to all three of those cases, because three out of four — 75% — of the siblings tested do show traces.
But what about the Trans-Ural Peneplain? The “dominant group between the tundra and the steppe in Eurasia’s northwest … from the area where the North European Coastal Plain joins the forests of Central Siberia.”4 One has it, three don’t. Eastern Afroasiatic? A group that “developed in the Persian Gulf north toward the Zagros Mountains.”5 One has it, three don’t.
How can this be?
We have to keep in mind 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 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, not just Family Tree DNA. I’ve tested with them all, and 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.
It isn’t soup yet.
And because we aren’t about to go digging up those old bones, it may never be soup.
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.
Bottom line: 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 friends don’t let friends do DNA testing only to get these percentages.
- 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.” ↩
- “Population Clusters in myOrigins,” Family Tree DNA Learning Center (https://www.familytreedna.com/learn : accessed 17 May 2014). ↩
- Ibid. ↩
- Ibid. ↩
- Ibid. ↩