Monday, 10 December 2012

23andMe adds ancestry composition

Up until last week 23andMe's analysis of my overall ancestry was 100% European and Near Eastern, 0% African, 0% Asian. That's 100% dull.

It is entirely consistent with my analysis from Family Tree DNA, 84.25% European (Western Europe), 15.75% Middle East (Jewish).

A few days ago 23andMe upped their game when it comes to examining what your DNA tells you about your ancestral origins. The new more detailed presentation is called Ancestry Composition and it's based on data from the Human Genome Diversity ProjectHapMap, and the 1000 Genomes project.  It tells you what percent of your DNA comes from each of 22 populations worldwide reflecting where your ancestors lived 500 years ago. Here's the default display for my results.


It's graphically more interesting, but the information isn't greatly different.

But wait, there's more.

Three levels of estimate are built in, conservative, standard and speculative. My conservative estimate decreases the European fraction to 95.5% transferring the remainder to Unassigned. The speculative estimate increases the European fraction to 99.1%.

You can simultaneously select three levels of regional resolution, global (the default), regional and sub-regional.

Staying with the speculative estimate and moving to the sub-regional resolution the analysis become more interesting.

The largest sub-region in my DNA is 45% associated with British and Irish, followed by 19.1% Ashkenazi, and then 16.1% non-specific Northern European.

That's more like it! Three quarters of my ancestry based on paper records is British, one quarter Jewish, not all of that Ashkenazi. If I revert to the conservative estimates the British and Irish fraction is mostly thrown into the Nonspecific Northern European and Nonspecific European categories. However, the Ashkenazi fraction is only marginally decreased, to 17.3%.

Perhaps the most innovative presentation, called split view, depends on having DNA samples from a parent and child. In my case my mother provided a sample prior to her recent passing. Here's the analysis of my DNA for the speculative estimate at regional resolution.


At this level  22.3% is Northern European from my mother. At sub-regional resolution that breaks down to 11.3% associated with Britain and Ireland ancestry. 18.3% is Ashkenazi. The DNA inferred as inherited from my father is 49% Northern European including 34.4% British and Irish at the sub-regional level.

There's a lot of background information on the 23andMe website. It would be good if there was a clearer statement of the error bound on the percentages. Is 0.3%, or 3%, within the likely bounds of error, to be zero for the various estimates and resolutions?

I suspect this 23andMe improvement to 22 sub-regions was stimulated, at least in part, by the improved geographic resolution being promised by the new Ancestry DNA product. The new Geneographic Project 2.0 offers just nine regions.

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