Tag Archive | Admixture

My Recent Talk on BioAncestry

The interpretation of the origins of your ancestors from your DNA is called different things by different companies: ancestry composition, admixture, or, incorrectly, ethnicity. The latter term is borrowed from anthropology and refers to a shared cultural heritage and does not necessarily include shared DNA although it often will. Click here for the definition of ethnicity onlineAnn Turner and Debbie Kennett, two genetic genealogists I admire, both like the word bioancestry instead of ethnicity, so that is the word I will attempt to use from now on.

I did a recent talk for the Southern California Genealogy Society’s (SCGS) webinar series on why the predictions vary so much from company to company and whether they are at all accurate. The slides are here and the webinar, free to SCGS members, is archived here (log in to view it). Click here for the schedule of SCGS webinars.

I explained that each company has different reference populations and they were originally focused on Europeans. I suggested reading the article at the ISOGG wiki (click here). I discussed that our ancestors moved around more than you might realize so that bioancestry predictions are not accurate at a country level. Your admix can mainly be determined on a macro scale: the North, South, East, and West of each continent. Some populations were isolated and inbred and thus are easier to predict from the DNA.

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Ancestry Composition Comparisons: a Case Study

Discovering where your ancestors came from is one of the more popular reasons to do a DNA test but the current ancestry composition algorithms have a long way to go. Sometimes East Asian ancestry is actually American Indian and South Asian might be gypsy or Indian Indian. Scandinavian might be British or North German and British and Irish might be Scandinavian.

Most efforts to analyze the deeper roots of your ancestry are based on samples of modern populations who self report four grandparents of a single ethnicity plus some public databases and a few ancient samples. Since each company relies greatly on their own databases of tested people, it is not surprising to see differences in their predictions.

My brother's Ancestry as shown at DNA.land

My brother’s Ancestry as shown at DNA.land

Since my brother is tested at all three companies I thought I would post the images of what each company sees in his DNA as well show the new report from DNA.land and a few from GEDmatch (both using his uploaded Ancestry.com DNA data). We are confident of our recent ancestry: 50% Southern Norwegian, 25% Bavarian German and 25% Ashkenazi.

The new DNA.land report is shown above, Hmmm, only 16% Ashkenazi.

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Phasing: or how to look at what you inherited from one parent only

So in the images in my last post about GEDmatch you may have noticed that my Dad has less Mediterranean, Siberian, and Southwest Asian than I did. Perhaps you are wondering if there is a way to see what I got from my mother? Separating what you got from which parent is called phasing and you need to have at least one parent tested and uploaded to use this function at GEDmatch. The Genetic Genealogist has a good explanation of phasing in this blog post – http://www.thegeneticgenealogist.com/2012/06/07/gedmatch-com-adds-phasing-tool/

Here is what I got from my mother although GEDmatch cautions that the phased data may not be all that accurate.



Eurogenes 12b does not have as many Northern breakouts but does include Finnish which is of interest since Dad has several Finnish matches so I collected all the Finnish percentages. As you can see Mom had some too and Shipley got more than I did:

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GEDmatch: a wonderful tool

One of the best tools around for genetic genealogy is the GEDmatch site which allows you to upload your raw data from whatever service you used and compare it to everyone’s data at GEDmatch in many different ways. But my favorite tool is the pretty pictures of your ancestry mixtures (called admixtures). Here is mine using the Eurogenes K12 calculator which seems best for us Northern/Scandinavian folk:


What does it all mean? A discussion of these populations is here at the Eurogenes blog.

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