By Christine Willmsen The Seattle Times
WWR Article Summary (tl;dr) How accurate are these DNA ancestry tests, and what are the pitfalls of using them to learn about our race, ethnicity and heritage?
The Seattle Times
In the quest to know more about ourselves, some are fortunate enough to scour through black-and-white family photos and listen to stories about ancestors from generations ago. Others hit dead ends because slavery, war or adoption have made it impossible to trace their roots.
Now millions of people are spending money on mail-order DNA tests to discover their genetic makeup as a way of understanding more about their history.
In ads on television and in our Facebook feeds, DNA companies like Ancestry.com promise to "uncover your ethnic mix, discover distant relatives, and find new details about your unique family history" with a DNA test.
But how accurate are these tests, and what are the pitfalls of using them to learn about our race, ethnicity and heritage?
I was skeptical of the accuracy of DNA ancestry tests, based on conversations I'd had with scientists, so I had my own DNA tested by two companies. Then I dug deep into my own background to determine their validity.
I chose the popular Utah-based Ancestry.com, which also connects subscribers to distant relatives, and Ohio-based DNA Diagnostic Center, which operates homedna.com.
DNA companies measure a minuscule percentage of the human genome and determine results by comparing someone's DNA to a proprietary group of samples they have collected. Depending on the makeup of those samples, DNA companies will miss some regions and populations of the world and overrepresent others in their pool.
The Seattle Times paid $199 and I mailed a swab of skin cells from the inside of my mouth to DNA Diagnostic Center. It measured 144 markers that show genetic differences among four populations: Africans, Europeans, East Asians, and Native Americans.
According to the results, which are estimates, I am 87 percent Caucasian and 13 percent sub-Saharan African.
This caught me off guard, and it would be just one of many surprises I unearthed during this quest.
Based on what my parents told me, I always thought of myself as a "Heinz 57" kind of woman, with a mix of German, Irish, Scandinavian and Canadian French.
"Persons with 85 percent European and 15 percent African generally exhibit few, if any, physical features characteristic of the African Group, such as dark skin," states the DNA Diagnostic Center manual.
But if I were one-eighth black, then my father or mother would be an even greater percentage, and two or three generations ago a relative probably would have been visibly darker.
The 23-page manual offers a lot of caveats about results. In my case, the company said while the "maximum likelihood estimate" is that I'm 13 percent sub-Saharan African, I could also be as low as 3 percent or as high as 23 percent.
I contacted Dr. Michael Baird, chief scientific officer at DNA Diagnostic Center, for more answers.
"I can't speculate where the 13 percent came from or how far back, but it does show a fair amount of sub-Saharan in your genome," he said. "But it could mean it was fairly recent, even, or some underlying sub-Saharan on both sides for many generations."
Born a skeptic, I waited for the Ancestry.com results after spitting in a plastic vial.
The $99 test analyzes markers of people who best represent each distinct ethnic group in the world.
The results claimed I am 100 percent Caucasian, with 37 percent from Ireland/Scotland/Wales, 28 percent from Europe West (Germany, the Netherlands, Belgium and Luxembourg), 11 percent Europe South (Italy and Greece), 10 percent Europe East, 5 percent Great Britain, 3 percent Finland/Northwest Russia, 3 percent Iberian Peninsula, 2 percent Scandinavia and 1 percent European Jewish.
But I was shocked yet again when, close to publication, Ancestry.com changed its estimates of my ancestry, concluding I was no longer Italian/Greek, Eastern European, Finnish, Iberian or Jewish.
I was a bit disappointed. I always wanted to be part Italian.
"More data and new methods of DNA analysis have given us a better picture of which DNA sequences are, or aren't, associated with specific world regions. ... New data indicates that a region does not belong in your results," it stated.
Ancestry.com had no comment but the website stated it shrinks and enlarges some regions and claims the estimates could change again.
For example, now it estimates that 41 percent of me is from England, Wales and Northwestern Europe, 26 percent from Ireland and Scotland, 20 percent from Germanic Europe, 9 percent from France and 4 percent from Sweden.
My aunt and my mother both were surprised by the homedna.com results saying I was approximately 13 percent black.
When I called them with the first results from Ancestry.com, they thought most of it made sense, like the finding of German and Irish. Then it turned comical when recently I told them I have an "updated estimate" of my DNA and guess what, I'm apparently from England, Wales and Northwestern Europe.
Seriously, I've never heard family members say our distant relatives came from Great Britain. And U.S. census records show several of my relatives as recent as my great grandmother reported being born in Finland.
Jennifer Raff, University of Kansas assistant professor of anthropology, said DNA companies estimate who you are most closely related to, but migration may have affected where your ancestors actually lived.
Results should be carefully interpreted, she warned: "Don't derive your identity from DNA."
Faced with dramatic shifts within one company's DNA results and the huge disparity between my results from two different DNA companies, I dug deeper.
Suddenly I was scouring census reports, researching baptisms and looking at gravesite photos online to validate or invalidate the results. Secretly I crossed my fingers, hoping to discover ties to royal lineage or famous people.
My mother had little information about her family, but census records supported my original Ancestry.com results, showing the Boyles immigrated from Ireland, to Burlington Township, Wisconsin, where they became farmers in the 1850s.
As I poked into the past, my mom told me about a family accident I'd never heard before, one in which my grandfather accidentally shot and killed his older brother while they were hunting as teenagers.
Had I not delved into the past, I'd have never discovered the secret tragedy that affected so many in my mom's family, leading some of them to turn to alcohol to cope with the loss.
On my father's side, I had been told, and Ancestry.com confirmed, that some of my relatives were French Canadian and part of a "genetic community" of French settlers along the Saint Lawrence Valley in Quebec.
My fifth-great grandfather Charles Girard (1750-1829) was born in Quebec shortly before the Seven Years War, during which the British and French battled for the Canadian territory. By 1887 several Girards had moved to states like Michigan and Minnesota.
If I believe Ancestry.com's updated DNA results, I'm mostly English or Welsh, something its own genealogy website and my family records, at this point, don't support.
And while it's unlikely I'm sub-Saharan, it's not impossible. Frankly, I'm not sure what to believe.
While some of the DNA results confirmed what I already knew, I also discovered my roots and how my ancestors, mostly farmers and miners, struggled. For that, this proud Midwest girl is thankful.
But it also leaves me wanting to know more.