Genetic Groups on MyHeritage: 3 Mapping the Past, or Not

 

MyHeritage AJ Genetic Group 5215, distribution 1850-1900

Ashkenazi Genetic Groups
MyHeritage has discerned 24 distinct genetic groups for Ashkenazi Jews, based on their analysis of the autosomal DNA of the people who have tested with the company. I must say before we even start, that I don't think this has ever been attempted before. It is a huge advance on the vague, confusing and inaccurate "Ethinicity Estimate" approach that they and other companies have been using up till now.

I must also say that unfortunately, the most visually appealing element of the initial roll-out of Genetic Groups, the historical distribution maps, are presented in a highly misleading way. This post attempts to explain how this happens.

My 5 GGs
MyH has allocated me to 5 of the 24 AJ groups, which in itself is of interest. It suggests that I do not have much, if any, genetic affinity to the members of any of the other 19 groups. In other words, AJs are not all related to each other. It suggests that our endogamy is within our own genetic groups, and not across them. Which makes sense, but also raises an intriguing issue: many of these AJ Genetic Groups appear to cover quite wide geographical areas (see the map in the post First Thoughts), and many of these Groups appear to be in the same areas at the same time. How did they manage to keep the groups genetically distnct? Did they not inter-marry?

Also of interest, to me at least, is the fact that I do not appear to connect to any of the Sephardic Groups. That knocks that family myth on the head.

From Trees to Maps
One of my AJ groups is numbered 5215. About half the people in Genetic Group 5215 have posted family Trees on MyH. The company has used the location information included in these Trees to map the geographical distribution of the ancestors of group members over time. 

The map above purports to show where the ancestors of the members of Genetic Group 5215 were living in the period 1850-1900. There are other maps for each of the 50-year periods between the years 1600 and 2000, and it is highly instructive to see how the distribution of population shown on these maps evolves over the years.

A bit of a puzzle
The families of all 4 of my grandparents are documented in Eastern Europe in the period shown on this map - my mother's side in Central Poland, and my father's in Belarus. The map above shows a just a light smattering in Belarus, some in Central Poland, some in the Austria-Hungary area, and stronger concentrations in the Netherlands and in Britain. Were my 5215s really more concentrated in England than in Belarus or Poland in the late 19C? This is a bit puzzling, because we know that the mass immigration of Jews from Eastern Europe to the UK only began after 1880, and the bulk of it was after 1900. So why does the map suggest otherwise?

A little look at Belarus
Before we delve further into this, let's have a closer look at Belarus.

When we zoom in on Belarus in the 1850-1900 map, we can see that the 5215s are indeed represented in my three paternal-side areas - my Schreibmans and Zaturenskys are from Pinsk (bottom left), my Levins from Gomel (Homyel, bottom right), and my Ilyutoviches from Lida (upper left). But there are some wide open spaces in between. Some of my other Genetic Groups have even less presence in Belarus, so this might still be an indicator that this is indeed where my families are from. Unless, of course the pinpointing of these three areas has arisen at least in part from the information I have put into my own MyH Tree - in which case, we're going round in circles.

Pause for thought
At this point, we should pause, and remember where the information that has gone into these maps comes from. MyH has found that amongst the people who have tested with them, there are 1330 whose autosomal DNA is sufficiently aligned to justify the creation of a Genetic Group specifically for them, GG5215. Just under half of these - 623 - have Trees on MyH. The company has combed those Trees for whatever ancestral date and place information it can find, in particular births, marriages and deaths. It then maps this material in 50-year periods. So far, so good.

However, what they have not done, and cannot do, is DNA-test all the ancestors that appear on those Trees. They may not all be GG5215s. In fact, we know that many of them are not; for a start, they have allocated me to 4 other AJ Groups. The descendants who have tested may show sufficient genetic characteristics to warrant being allocated to this Group, but many or most of them will also have ancestors from other AJ Groups, or who are not AJ at all.

For instance
A couple of examples from my own case will illustrate this point. As I mentioned before, half my ancestors are AJs from Poland, half AJs from Belarus. I have both sides documented in those places back to +/- 1800. So I would be happy to accept that GG5215 covers both areas, and both sides of my family. But none of my genetic ancestors were in western Europe or the UK in that period, and I very much doubt that any of the AJ ancestors of other members of the group were there either, for the reasons outlined above. So what is the genetic connection between GG5215 members and these places? It can only be that some of them have ancestors who were not AJ. So I'm expecting to see evidence of non-AJ ancestors in the Trees of at least some of my fellow GG5215 group members, and specifically of ancestors from Western Europe and Britain.

Close to home
And I don't have far to look. Consider my 1C1R (first cousin once-removed), Katy. We share my paternal line - her grandfather was my Uncle Mick, my father's brother. Mick married Margaret, a non-Jewish English woman, so although Katy got enough of the characteristic GG5215 DNA from Mick to qualify for the Group, she also has 25% English ancestry through her grandmother Margaret. MyH have picked her English ancestors up from her Tree, and put them on the 5215 map. Where they don't belong.

And this is all exacerbated by the fact that people with English ancestry can generally take their lines much further back that AJs can, with the exception maybe of a handful of rabbinical lines, and this applies to places as well as names. So when you look at the earlier maps for GG5215, you find that the places where records are available show up much more strongly than those where they're not. And the further back you go, the greater the disparity, and the more skewed the results will be. 

Reductio ad Absurdum
And you end up with this absurdity:

MyHeritage AJ Genetic Group 5215, distribution 1600-1650

But there weren't any Jews in England in 1600-1650.

They had been expelled in 1290 and were not re-admitted until 1656. (See From Expulsion to Readmission, by Ariel Hessayon, for the background to both of these episodes). And even then they were mostly Sephardim, originating from Spain and Portugal, not AJs - including no doubt my GG5215 ancestors - who to the best of our historical knowledge, originated in Germany, moved towards the east in the late Middle Ages, and were by 1600 well established in Poland and probably settling in Belarus as well.

So whilst these maps do represent my GG5215 ancestors, to the best of our limited collective knowledge, they also represent the ancestors of all members of 5215 who have Trees on MyH. And this includes those of their ancestors who were not 5215ers, or not Jews at all, and could have come from anywhere, especially, it seems, from Southern England and the Netherlands.

So it's not my ancestors on these maps, it's theirs.