Tag Archive | Ancestry Compostion

Ancestry Composition Numbers by Segment at 23andme.com

Did you know 23andme now provides the segment data for its ancestry composition assignments? This is a pretty recent feature and might even be useful. Unlike the other companies, 23andme does its admixture (aka ancestry composition) in chunks. This may make it more accurate than the others but in any case it means that they can give us the segment numbers. Then we can compare those to our matches.

To get these numbers, first pull down the reports menu and click on ancestry. On the initial ancestry page click on Ancestry Composition or the > symbol next to your highest group. Both are marked with my red arrow below.


The next page, the ancestry composition page has the pretty chromosome picture with ancestries displayed where you can change the confidence level from speculative (50%) to conservative (90%). To get a CSV file of the segments you click on Scientific Details at the top or the bottom of this page.


Then scroll all the way to bottom of that next page until you see this. You can select your confidence level as well for your downloaded data.


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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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