Have you seen the latest from the Irish DNA Atlas Project?

+7 votes
asked in The Tree House by Veronica Williams G2G6 Pilot (114k points)

Just FYI, info about this study was posted here on G2G a few days ago: https://www.wikitree.com/g2g/519939/seen-distinct-autosomal-populations-ireland-great-britain. And the first link is invalid: has an extra comma included in the URL: https://www.irishtimes.com/life-and-style/abroad/new-irish-dna-atlas-maps-genes-of-the-people-of-ireland-1.3331369. The Irish Times article is worth a glance, maybe before reading the PDF from Nature.

1 Answer

+5 votes
The Irish DNA Atlas achieves a degree of precision that far exceeds Family Finder. I take into account that it was highly selective, with criteria that would exclude most FTDNA customers from the Irish diaspora. It is still impressive that they can get down to provincial level, whereas Family Finder uses multi-nationaL agglomerations like “Western Europe”. Yet 23andme manage to identify smaller blocks like “France and Germany” which I take to be the Norman French part of my ancestry, and “Scandinavian” to be the Viking part of my ancestry. 23andme also detected  >1% Ashkenazim, which could be one ancestor just seven generations ago (their estimate). Interesting to firstly compare 23andme’s more specific report with Family Finder’s vague report, then to see the specificity and precision of the Irish DNA Atlas.
answered by Rory Cain G2G6 (7.7k points)
To have been eligible to join this project I understand you needed to have great great grandparents all born in the same geographic area, hence the greater precision in results.

But as a point of information, "Western Europe" basically means "France and Germany", for the most part, and publishing "smaller blocks" doesn't necessarily make it more accurate any more than adding decimal places necessarily adds to it's precision. You SHOULDN'T add those decimal places if they're not significant, but that doesn't mean people won't do so ANYWAY.
I guess “ Western Europe” can be almost anything you want it to be. There are people who use the term to encapsule everything outside of the former Soviet Union. That’s probably the broadest definition. For other, “Western Europe” seems to be the area where Romance languages and Germanic languages prevail. I don’t believe I have ever previously seen a definition of “Western Europe” as narrow as just “France and Germany.” I wonder what the Irish, British, Spanish, Portuguese, Belgians, Dutch, Luxembourgers & others universally accepted as Western European would think of being excluded. The Wikipedia definition of Western Europe is rather conservative, and includes all those nations. Others would include Scandinavia, Switzerland & other nations. If we went back in time some 15 years or more, we may not have had the DNA markers to distinguish Celtic from Germanic or Italic, but we can do better in this day and age. My 23andme test is 8 years old and did better. To me, equating “Western Europe” with “France and Germany” is Chris mpsring apples and oranges. They are never going to match.


Perhaps you could point out where I used decimal fractions? Personally I doubt that anyone can be that precise, given that “whole genome” or “fulL Y” testing is far from that, given the gene sites that cannot be read, such as the palindromic zone. I agree with you that decimal fractions suggest a degree of accuracy that we have not yet achieved. I just don’t see where I fell into that error.
I've noticed that 23andMe results apparently involve some interpretation, especially in those miniscule percentages, so they're not cut & dried.  For example, when my results were first posted, they showed me as 100% European. When my mother (who had <0.1% Native American) and I subsequently linked our records, my results shifted, so now I'm 99% European and <0.1% Native American.  Obviously, there is something in my DNA which could be interpreted either way.  Perhaps the Ashkenazi result is a similar situation.

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