The media has blasted headlines this week that show an incredible ignorance of DNA testing for ethnic percentages. One, which could have been pulled out of a 1980s tabloid for its ridiculousness, screeched, "Neo-Nazis are taking genetic tests and are deeply upset by the results!"
Neither of the two writers delved too deeply into the subject, and that is because shorthand reporting is easier. As we've posted, again and again, most of the three major DNA testing sites disclose quite openly that their science is far from perfect. For example, that if one is German, French, Dutch, Belgian, Austrian, or Swiss, that they cannot discern your ancestry 92% of the time. (With the US having more people of German ancestry than even English or Irish -- that's a big deal).
In fact, it's quite common for someone taking a test from three different websites to receive three different results! And as the post beneath this one shows, trying the 40 or so other "ethnicity calculators" available for free on Gedmatch produced...40 different results.
As I often say: if 5 different scales produced 5 (vastly different) weights, you would know that at least four of 'em don't work! :-)
Anyway, for those looking for perspective, we shouldn't highlight the bad, so we've decided to highlight the good -- or the excellent, rather.
One of the best posts we have seen on the topic comes courtesy of a blog called The Legal Genealogist. It's called, "Those Percentages If You Must" -- and is a Must Read for people curious about whether ancestry calculations from DNA tests are accurate.
It first, rather hilariously, goes into the various myths and misperceptions about DNA and human history. Concepts like, "black Irish" or "I have some Native American in me." Concepts that plague the world of pop-DNA-testing.
After it goes through the science (in easy to understand terms), it reveals what I have posted here time and time again:
DNA testing IS GREAT and REMARKABLY PRECISE for finding you cousins. It CAN tell you if you are a third-cousin, once-removed (with that kind of precision). If you don't know your heritage, and that cousin is, for example, 100% Native American -- then it follows that you too have a pair of Native American great-great-great grandparents.
DNA testing IS NOT good at ethnicity percentages and ethnic calculation. As if anything could be so precise as to tell you that you are "4.2% Jewish." The science is still just not ready for prime time, and many underrepresented populations, even in Europe, still confound the tests.
(As an aside, ancestry calculators should all produce nice and even results when people get back to the pre-travel era." In other words, if you had 64 ancestors that were alive in 1500 AD, you should only see multiples of 1.56% chunks, right? Since no one is half a human!)
The article succinctly concludes with:
DNA testing is a wonderful tool. It can connect us with cousins we’d
have never found otherwise to help us reconstruct our family histories.
But in terms of “am I Native American?” “what tribe did I come from
in Africa?” “am I 25% Irish?” No. No, no, no. That’s the absolute
weakest aspect of DNA testing.
Indeed. Well said.
Showing posts with label native american. Show all posts
Showing posts with label native american. Show all posts
Friday, August 18, 2017
Saturday, January 30, 2016
In Praise of Roberta Estes and DNAeXplained.com
In a world of pseudo-science and echo chambers, a few blogs stick out for being mostly in touch with reality. In the world of Ancient DNA, Dienekes, although less active than before, has pioneered much in the field of DNA, and still has many serious scientists who comment there.
In the world of DNA for Genealogy, one blog sticks out. It is Roberta Estes' DNAeXplained.com. Of all the blogs and websites dedicated to disseminating information about DNA, hers is consistently factual, science-based, and yet easy to understand.
This scientist came across a few of her posts, and I daresay they are mandatory reading for anyone seeking a better understanding of their DNA. Below are links and highlights:
Step 1: Creation of the underlying population data base.
Don’t we wish this was as simple as it sounds. It isn’t. In fact, this step is the underpinnings of the accuracy of the ethnicity predictions. The old GIGO (garbage in, garbage out) concept applies here. . . .
The third way to obtain this type of information is by inference. Both Ancestry.com and 23andMe do some of this. Ancestry released its V2 ethnicity updates this week, and as a part of that update, they included a white paper available to DNA participants. In that paper, Ancestry discusses their process for utilizing contributed pedigree charts and states that, aside from immigrant locations, such as the United States and Canada, a common location for 4 grandparents is sufficient information to include that individuals DNA as “native” to that location. Ancestry used 3000 samples in their new ethnicity predictions to cover 26 geographic locations. That’s only 115 samples, on average, per location to represent all of that population. That’s pretty slim pickins. Their most highly represented area is Eastern Europe with 432 samples and the least represented is Mali with 16. The regions they cover are shown below. . .
No matter which calculations you use relative to acceptable Margin of Error and Confidence Level, Ancestry’s sample size is extremely light. . . .
"having Haplogroup Origins and Ancestral Origins indicating Native American ancestry does not necessarily mean you are Native American or have Native American heritage. This is a very pervasive myth that needs to be dispelled. . . .
The good news is that more and more people are DNA testing. The bad news is that errors in the system are tending to become more problematic, or said another way, GIGO – Garbage in, Garbage Out.
....
There are a very limited number of major haplogroups that include Native American results. For mitochondrial DNA, they are A, B, C, D, X and possibly M. I maintain a research list of the subgroups which are Native. Each of these base haplogroups also have subgroups which are European and/or Asian. The same holds true for Native American Y haplogroups Q and C.
In the Haplogroup Origins and Ancestral Origins, there are many examples where Non-Native haplogroups are assigned as Native American, such as haplogroup H1a below. Haplogroup H is European...
One of the problems we have today is that because there are so many people who carry the oral history of grandmother being “Cherokee,” it has become common to “self-assign” oneself as Native. That’s all fine and good, until one begins to “self-assign” those haplogroups as Native as well – by virtue of that “Native” assignment in the Family Tree DNA data base. That’s a horse of a different color.
In the world of DNA for Genealogy, one blog sticks out. It is Roberta Estes' DNAeXplained.com. Of all the blogs and websites dedicated to disseminating information about DNA, hers is consistently factual, science-based, and yet easy to understand.
This scientist came across a few of her posts, and I daresay they are mandatory reading for anyone seeking a better understanding of their DNA. Below are links and highlights:
Don’t we wish this was as simple as it sounds. It isn’t. In fact, this step is the underpinnings of the accuracy of the ethnicity predictions. The old GIGO (garbage in, garbage out) concept applies here. . . .
The third way to obtain this type of information is by inference. Both Ancestry.com and 23andMe do some of this. Ancestry released its V2 ethnicity updates this week, and as a part of that update, they included a white paper available to DNA participants. In that paper, Ancestry discusses their process for utilizing contributed pedigree charts and states that, aside from immigrant locations, such as the United States and Canada, a common location for 4 grandparents is sufficient information to include that individuals DNA as “native” to that location. Ancestry used 3000 samples in their new ethnicity predictions to cover 26 geographic locations. That’s only 115 samples, on average, per location to represent all of that population. That’s pretty slim pickins. Their most highly represented area is Eastern Europe with 432 samples and the least represented is Mali with 16. The regions they cover are shown below. . .
No matter which calculations you use relative to acceptable Margin of Error and Confidence Level, Ancestry’s sample size is extremely light. . . .
"having Haplogroup Origins and Ancestral Origins indicating Native American ancestry does not necessarily mean you are Native American or have Native American heritage. This is a very pervasive myth that needs to be dispelled. . . .
The good news is that more and more people are DNA testing. The bad news is that errors in the system are tending to become more problematic, or said another way, GIGO – Garbage in, Garbage Out.
....
There are a very limited number of major haplogroups that include Native American results. For mitochondrial DNA, they are A, B, C, D, X and possibly M. I maintain a research list of the subgroups which are Native. Each of these base haplogroups also have subgroups which are European and/or Asian. The same holds true for Native American Y haplogroups Q and C.
In the Haplogroup Origins and Ancestral Origins, there are many examples where Non-Native haplogroups are assigned as Native American, such as haplogroup H1a below. Haplogroup H is European...
One of the problems we have today is that because there are so many people who carry the oral history of grandmother being “Cherokee,” it has become common to “self-assign” oneself as Native. That’s all fine and good, until one begins to “self-assign” those haplogroups as Native as well – by virtue of that “Native” assignment in the Family Tree DNA data base. That’s a horse of a different color.
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