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Frederator 11th November 2017 07:22 PM

Irish Correspondences
 
For the first time I notice that I'm having some limited success in getting accurate results from the ethnicity calculators at Gedmatch, specifically MDLP Project K16 Modern.

But only a rough kind of success. With a very vague sort of geographical correspondence between the returned reference populations under the 4-factor analyses and the ancestral homes on my paper trail. With notable exceptions that I mostly attribute to the donors' inheriting a less than perfect 25% grandparental contribution across the board.

Elsewhere I've hypothesized to some of my matches that Sicilian ancestry may be reported as Greek, Macedonian or Albanian. I don't have any such ancestry myself, but just made a rough guess based on a crude knowledge of historical settlement in Sicily.

But I've also noticed something else.

Closer to home, I've noticed that about a half dozen of my Irish-born matches consistently show Polish or Belarusian components to their ancestry. Interestingly, this small sample of folks are all from Co. Roscommon or adjacent parts of Co. Galway. Any other Irish folks notice similarly strange patterns?

I'm not suggesting that there is any recent or even remote historical migration between these places. Just wondering whether through happenstance that some sub-set of alleles regionally prevalent in east Connacht might consistently approximate markers typical in parts of Poland/Belarus.

I know it's weird, but so too is the apparent correspondence I noted in my small pilot sample.

Just wondering.

wombat 11th November 2017 11:19 PM

GEDMATCH is tricky to use and you can't always take the Oracle stuff super seriously.

That said, I know that tens of thousands of Scottish actually went to Poland and the Baltics in the 1600-1900 period. In fact, we were shocked when tracing back my mom's Baltic German line that we hit upon the surname Barclay for someone born in the 1700s! And then we just found that a Baltic German cousin in Latvia in the 1900s married a Baltic German who turned out to be 75% German and 25% Scottish. We were surprised to see one of his grandmothers listed as being born in Scotland and even more shocked to get MyHeritage tree matches for that person. And the trees we matched to were like all 100% Scottish and none of them had a remote clue that they had someone go off to Latvia. Interestingly that couple got married in both Riga and in Scotland and the people back in the UK/US guessed that the man she married was Scottish! They had no clue he was Baltic German from Latvia. As it turned out they returned back to Latvia right away again and had kids there, but I suppose it could go the other way at times. Mostly what I see back then seems to be the wrong direction though for what you are looking for.

FWIW my dad who is mostly Latvian gets a decent number of people who seem to have ultra Irish backgrounds. Not yet quite sure what it means.

dna 12th November 2017 02:31 AM

Quote:

Originally Posted by wombat (Post 445384)
[----]
FWIW my dad who is mostly Latvian gets a decent number of people who seem to have ultra Irish backgrounds. Not yet quite sure what it means.

Let me venture a guess... :) Scottish migration was both to Baltics and to Ireland ? ? ?


Mr. W

Frederator 12th November 2017 08:46 AM

Just repeating for the sake of emphasis, but I'm just about 100% sure that there was no meaningful traffic between Co. Roscommon and Belarus.

Scotland's Baltic connections are an interesting if little discussed phenomenon, but there is just about zero percent chance that that is relevant to the cases I'm talking about. The people I'm talking about are from pretty vanilla Catholic backgrounds, and in any case, any link through Scotland would have been so remote as to stand zero chance of showing up as 25% or more of a person's total contribution.

It's just a simple fact that the looser definition applying to the ethnic-level of marker aggregation (as contrasted with the more rigorous genealogical-level) is bound to turn up false positives from time to time. It also makes sense that 'convergence' is more likely to be a factor where the marker definitions are so much looser.

I'm hypothesizing that the latter just might be the case here: that one set of marker values might legitimately define two un-related populations--Belarus nationally, and Roscommon/Galway hyper-locally.

The law of large numbers says that a very weird but isolated and meaningless observation is inevitable any time the total volume of observations is high enough. The only thing that made me think that this might not be completely random was that I made the same observation in a handful of people from the same area.

dna 12th November 2017 04:28 PM

If scientifically proven, existence of convergence in the realm of autosomal matching would drive people insane. Is it only your hunch or there are already papers discussing the phenomena?


Mr. W

Frederator 12th November 2017 04:36 PM

That's just one interpretation of a half dozen personal observations. That's why I was soliciting responses from other users, to determine whether there is something more systematic to it than these few people.

Frankly, you surprise me with your response to the idea of convergence at the ethnic level of autosomal interpretation. Any time you relax your criteria for identifying a match--which ethnic calculators most certainly do with respect to genealogical matches--you have to recognize that you are increasing the odds of false positives generally, of which convergence is just a special instance. That's just the inverse nature of Type I and Type II risk.

Anyone emotionally unprepared to admit that these risks pertain to ethnic calculators as well must be very fragile.

dna 12th November 2017 06:39 PM

Oh, thank you :) . I will sleep well, as luckily for me my education included statistics, stochastic process, probability etc.

In my family, there is C. (Child) with 4% in Asia Minor. Not only his parents A. (Adam) and B. (Barbara) are 100% Europeans, but the children of C. do not have it. Siblings of A. and B. and a variety of their cousins do not have Asia Minor either.

The error in myOrigin must be at least 5%. Or (non-exclusive "or")...

A. and B. are from populations that lived confined to their villages, separated by hundreds of kilometres, and for centuries (may be 1000+). So it is possible that their DNA combined into a pattern somewhat like that of a very different, distant population.


Mr. W

Frederator 12th November 2017 08:37 PM

I think the main problem with ethnicity calculators is knowing which level is best to aggregate at.

The only calculator that I am impressed with, just based on personal experience, is the MDLP Project K16 Modern 4-factor. It pretty much nailed my unphased and phased paternal kits, although I'm having trouble making sense of my brother's kit and my own phased maternal readings.

I'm pondering the notion that my success with MDLP is attributable to the fact that it employs a 4-factor format, which comes closest to mirroring my specific genealogy, which is comprised of lines from two major ethnic groups (Irish, German) and five distinct sub-groups: Baden-Wuerttemberg, Swiss, Ukrainian, Bohemian, and Irish, which due to the small size of that country I mostly don't bother to analyze on a more granular basis any more.

It's not perfect, but being able to make clear connections between each of the 4 MDLP factors and my paper trail gives me a greater (maybe illusory?) sense of confidence in the algorithm's rationality.

But I have real problems with my brother's results. At Gedmatch I can only make a clear correspondence for one grandparent on each side of our family. I even feel like I'm really reaching to do so for my own maternal phased results, although my mother's own unphased results match pretty nicely, and somehow, despite the greater complexity of my personal admixture, so do my own unphased results.

On the other hand, MyOrigins has just been an unmitigated failure for all of my family's kits. I'm not really surprised given the complexity of the admixtures involved. But this first taste of (relative) success with Gedmatch encouraged me to believe that there are some fundamental design principles to be derived from the contrast. Maybe like dis-aggregating at an appropriate level.

My thinking was that, in order to build on that foundational observation, I should try to look at 4-figure results for mono-ethnic individuals, like these Irish-born people, and see if there are any patterns in the way their individual components relate to one another.

Their one-factor analyses all return them as Irish, Scottish or, less often, English, which seems good enough as far as I'm concerned.

A handful of these people consistently show one factor out of four as Belarusian or Polish--usually paired off with another factor as French or Basque, with the remaining two Scottish or Irish. I know from those with posted pedigrees that they're pretty vanilla Catholics from the west with no hint of anything as exotic as the Baltics.

At the moment I don't know if those are just random noise or if there really are some important sub-national regional patterns at work. And it bothers me a bit. I don't have a unified theory on how ethnic calculators should work.

I can't have much confidence in my own obviously inaccurate one-factor results or the dubious 4-factor results of these Irish-born people if there is no consistent, objective basis for knowing which model to apply. It seems like nonsense to say that people in Europe should all use one-factor models. There is plenty of ethnic diversity within each country's population, although confusingly, not within my pilot sample.

RebeccaR 30th November 2017 10:27 PM

You're welcome to use my Father's GEDMatch if you like. On FTDNA he pegged out at
British Isles 75%
Iberia 13%
East Europe 6%
Southeast Europe 4%

On Ancestry he pegged out at
Ireland/Scotland/Wales 43%
Great Britain 41%
Europe East 5%
Iberian Peninsula 4%
Scandinavia 3%


We do have two known ancestors from Germany but none from Poland.

Our known Irish ancestor is not from the same location as yours:
Charles Gaffney
1723–1801
Birth 1723 • County Meath, Ireland
Death 10 DEC 1801 • Ross, County of Meath, Ireland
He is my 5th great-grandfather

I manage my Father's DNA and he gave me permission to liberally share. His GEDMatch # is A262160 if you want to one on one compare.

After I read what you wrote, I checked for Poland and yes I saw some on his too :)


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