DNA Ethnicity Test Result Reliability – It’s All About Expectations

Around Thanksgiving, I went to lunch with a group of childhood classmates. During a lull in the conversation, one of them asked – “Hey, who here has done their DNA?”  A number of us raised our hands. His next question was, “What did you think – was it right?” And I sighed a little.

Of course it was right. There are no wrong answers, and DNA really doesn’t lie. The real question he was asking (and he clarified this) is, “Were the ethnicity results what you expected?” For the first quarter of 2018, with an extraordinary number of tests sold during the holidays, we expect literally millions of new DNA test results to flood the test sites. The first thing most people will do is look to see if their ethnicity estimates match their expectations.

People take DNA tests for a lot of reasons.  For me and my close family members who have tested, it was to see if we could find matches to help us take our paper research back a few generations. For adoptees, it is the hope of finding biological family. But for an increasing number of people, it’s just to discover or confirm a cultural or ethnic identity or two. They’re sure they will find that Native American, Asian, or French link they’ve heard about in family stories. Or they KNOW they will be 50% Polish and 50% Irish. Especially in melting pot nations like the United States, there seems to be a longing to identify with a deeper, more long-standing heritage.

Ancestry.com© has a fairly famous commercial, where a man who embraced his German heritage completely – even wearing lederhosen to celebrate his culture – does a DNA test to confirm his ethnicity. He ends up discovering Scottish ancestry, whereupon he just trades in his lederhosen for a kilt. Never mind that when the commercial came out, Ancestry.com did not yet include either Germany or Scotland as a distinct region in their ethnicity results – meaning that the man had to do other research to make his leap. The idea that any company’s DNA admixture estimate alone gives you a complete and accurate map of your genetic heritage is just plain misleading. There are assumptions and subjectivities here, as well as missing data, in every report.

The trouble is, DNA doesn’t lie, but it’s whimsical – and it’s very, very random. And these reports go back, not just the 200 years most of our trees cover, but hundreds and hundreds, perhaps even thousands, of years. Ethnicities (admixtures) can go back to the Romans and their conquests. Back to the Vikings and their settlements throughout Europe and other parts of the world. Back to the Turks and Ottomans, to the Mongols, and to Polynesian migrations… And then there’s everything that happened in between those times and now. People are unpredictable. Borders and governments have changed dozens of times in Europe alone in the past 500 years. Germany has never yet been a unified independent country for 50 consecutive years – yet some of us look for a solid “German” identity in our DNA.

So what can we learn, and what can we understand about what the ethnicities in the reports actually do and don’t tell us?

First of all, DNA can’t always reliably give you the nationality (country) of your ancestors as you understand it – This is especially true in Europe because of the way borders changed and people moved around, inter-married, were invaded, and travelled to trade with other countries. Ethnicity estimates are much more reliable in giving you continental or regional identities. Many ethnicities overlap when placed on a map. My husband’s mom was Polish – both parents were born there in very different regions, and they were married in Warsaw – but there actually was no “Poland” for a period of time, and where its borders are now is not where they were when hubby’s ancestors lived there. Watch this animated map. There are multiple versions of this on the internet, some for other parts of the world as well, but this one works well for our purposes. Keep an eye on Poland. Watch again looking for Germany, then Russia…  Daily Mail’s Interactive Map of Europe over time.

For my mom’s Ulster Scots family, there is no way to actually determine where the Scots begin and the Irish end – there were multiple migrations between the two countries in our family as late as the 1850’s, so we inevitably have some of each through intermarriage. Unless we magically unearth a bunch of family Bibles from 1650 to 1800, we’re going to have to live with not knowing exactly which DNA is which.

My sister and I also have way more British Isles DNA in our results (on 3 sites’ results) than our mother’s 50% could possibly account for. When a paternal family member (who should have been “all German”) took a test, the results were about 20% English/British – YAY! Now my sister and I can choose to keep believing our mom’s Scots ancestors didn’t intermingle with those brutish Sassenach Englishmen! (You’re supposed to laugh here, because these are the kinds of feelings or beliefs we all bring to our first look at our ethnicity estimate reports, and because, after all we apparently still have that English DNA.)

Sis and I also each have a few “trace regions,” which the testing companies acknowledge could just be coincidence or noise – some people get very concerned about having traces from unexpected regions, when there may not actually be any actual link there at all, just some coincidental markers.

Next, each testing company has its own algorithm for analysis, and there is a certain amount of subjectivity in them. They each start with regions they select and then find “reference populations” – people they believe had all their ancestors in each specific area for a few hundred years. They then each select hundreds of thousands pieces (but not all) of your DNA to look at. When they find significant common markers between you and a reference group, they identify you with that “ethnicity.” Then, they use algorithms to weed out coincidental or other results which they believe may skew results. Every company publishes info on how they determine ethnicities (admixtures), and this is available for your review. It may really help to review the info links at each site as you review your results. Although there is considerable science involved in their assumptions, they are still assumptions:

  1. Ancestry
  2. 23 and Me
  3. FamilyTree DNA (FTDNA)
  4. MyHeritage

GEDmatch, which doesn’t do its own testing, but takes uploads of tests from other sites, has a variety of admixture analyses available as well. All of these providers are continually upgrading their results through a variety of methodologies, and although they are getting better, they will always rely on some suppositions – so none of them is ever going to be perfect, and all should be taken as estimates, not as reliable facts.

Last, your own DNA is a wild card. The way autosomal DNA (the kind ethnicity reports are based on) works, each person gets 50% from each parent. But no two people (except identical twins) get the same 50%. For all other siblings, it’s like being dealt a different random half of a deck of cards each time. In each generation, only a random half of each parent’s inherited gene pool is passed down to each child, and on the flip side, half is lost. Over hundreds of years (sometimes even less), some ethnicities may remain, and others may become lost or so small/fragmented that they aren’t statistically significant or identifiable anymore. You still had those ancestors, your DNA just didn’t hold onto enough of that DNA in one place to have them show up in an ethnicity estimate report. Your siblings or cousins may still have big enough pieces to see, though. This is why it’s important to test multiple family members if you are trying to answer specific questions. I have a full sister, verified objectively and subjectively – that is, by DNA, and by a nearly identical voice and other traits that each of us pretty noticeably has from each parent. We have differences in our ethnicity reports, though. We also share only about ½ of our DNA “matches” – meaning we each have a variety of people we match that the other doesn’t (yes, your DNA results can show you way more than just an estimated ethnicity.) Our results aren’t even a little unusual; this is common with full siblings.  What this tells us is that no one person’s DNA is a complete map of their ancestors, because of what’s been lost or minimized through random inheritance. Nobody’s DNA contains a complete family tree.

If you are looking for a particular ethnicity, use Google or Bing to search:  DNA ancestry __________  – filling in the blank with the ethnicity you’re searching for. There are tons of resources that will pop up. It may be that your Native American ethnicity is showing up under another description or descriptions. Or…

There are the more difficult possibilities. These include family stories being just that – fabricated or embellished stories that took on lives of their own through the years (we have a beloved French royalty myth in hubby’s Polish line) that may or may not have a basis in reality. Another possibility is that somewhere along the line, the parent or parents listed in the family tree are not the actual parent(s) of a child, unknown to succeeding generations. This could be the result of an informal adoption by a step-parent or other person(s), an affair, or other similar events. Genealogists call these NPEs (non-paternal or non-parental events). One of the most famous recent cases of this was Bill Griffeth’s. Bill was a longtime genealogy hobbyist and respected journalist when he tested his DNA and discovered that his ancestry was not what he expected. He wrote a wonderful book called The Stranger in My Genes detailing his difficult journey.

So we are back to expectations vs. results. DNA doesn’t lie (in rare cases of suspected test company error, the companies often do a free retest.) Two different TV news shows  (Inside Edition, and more recently the Today Show) tested groups of identical triplets at multiple testing companies. Although they found the tests weren’t 100% identical, they were pretty darned consistent overall. Your DNA ethnicity report won’t reliably give you the tiny island or county your recent ancestors came from, but it should give you a reasonable indicator of the regions or countries your genetic ancestors may have lived in.

It’s best to come to DNA testing without pre-conceived notions – many of us don’t even know the full names, dates, and birthplaces of our 8 great-grandparents with certainty. Three more generations back there 64 direct ancestors – how much do you know about them? You may or may not want to investigate any unexpected results if you find them, but you can’t completely discount them. Discover what random genetics may have given you. Things you don’t expect may appear, and things you expected may have faded away. No matter what any of us find here, we are all what both nature and nurture have made us, for better or worse.

The long and short of this is, you should test your DNA with the understanding that you should take any specific ethnicity estimates with a grain of salt, and that you may find some unexpected results. Upload your results to multiple sites to see what new things you find at each one. Test additional family members. But as many have said before me, don’t turn in your lederhosen for a kilt. You are likely a mix of cultures and ethnicities, and you may be made up of more than you ever imagined. Keep in mind that there are subjectivities in the test algorithms and missing pieces in your random DNA. DNA Ethnicity/Admixture estimates are just that. They can never tell the whole story because your own DNA doesn’t give it to them. All they can do is point you in a reasonable direction for a further research journey.  Bon Voyage.


Some Additional Recommended Reading:














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7 Responses to DNA Ethnicity Test Result Reliability – It’s All About Expectations

  1. Pingback: Are DNA tests accurate? | Jenealogy

  2. I hate those Ancestry commercials. The idea that myDNA determines what one should wear or how one should decorate is insulting and stupid. I am from the English speaking Caribbean. 54% of my DNS is of West African origin, over 43% is a combination of Scottish, Welsh and French origin, the rest is a mixture of Carib and Iberia DNA. So .. does that mean I should start wearing a kilt with a dashiki?


  3. Pazlo says:

    This is a curious subject. My son was not surprised to find “40% Irish” in his DNA results, along with a smattering from Europe (Sweden, primarily).
    Today my friend Joe was looking at his DNA stats with consternation. With an Italian last name, the family thought of themselves as Italian (like the guy on the commercial), but it turns out he’s mostly “Eastern European”, with a couple other significant identifiers that are not from Italy.
    It seems to be a surprise, maybe a bit of a shock to Joe. Almost an identity crisis (though Joe is so even-keeled the word crisis is overkill).
    I’ll be interested to hear what he thinks after it has a chance to settle in.



  4. KerryCan says:

    Fascinating post–so much valuable information!


  5. chava61 says:

    Recently I was asked to give a DNA sample by the US Military to help identify an unaccounted for great uncle who died as a POW during WW2 and whose remains were never identified. I am still waiting for results as military’s timeline is much slower than a commercial operator/operation.


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