Monday, October 10, 2016

Let's See How This Approach Works

Dear Mr. Pikholz, 
I tested my DNA with and I see on GEDmatch that I match twenty-six kits that have your email.
The names in my family are Cohen, Levy, Miller, Friedman, Blumenstein on my father's side and Goldstein, Goldberg, Feingold, Goldsmith and Kuperman on my mother's side.
Can you tell me how we are related? My GEDmatch number is A______.

Dear _______,
I manage about ninety kits and most weeks I hear from people like you who match thirty, forty, fifty and more. Those are generally weak matches with no segment larger than 15 cM. Usually 15 cM isn't much to go on, particularly when we have no surnames in common. (Much of that is on me because I do not have large numbers of surnames on my sides.)
I have begun suggesting that people do the following:
  1. If you are on Family Tree DNA, check the surnames of your matches with me, in the far right column and see if anything matches.
  2. Get on GEDmatch and search your kit using "one-to-many" but change the 7 to 15 or 20. That will eliminate the small matches. (You can always go back and look at those later.) Then sort on the "name" column. All my kits will come up together near the top. The middle part of the name tells you who is from which family, using the codes at .
Then we can talk, if you find anything significant.
For an example of how this can work, look at my blog post "Cousin Debbie" from last May. And note that although this was a very successful inquiry, we still were not able to be specific about the nature of our connection.

Thursday, October 6, 2016

Lazarus: The Odd Case of the Son and His Mother

One of the talks I gave at the recent IAJGS Conference in Seattle is "'s Lazarus Tool As It Applies to Two Kinds of Endogamy." This was a first-time presentation and the idea was three-fold:
  • to show some of the things you have to be careful of when creating a Lazarus kit in an endogamous population
  • to show how I used the Lazarus kit of my great-grandfather to further my research
  • to show how two the different kinds of endogamy - structural and personal - blend together to enable analysis that would otherwise be exceedingly difficult if not impossible
For those of you not familiar with the Lazarus tool (about which I have written several times, beginning here), GEDmatch reconstructs a partial genome based on DNA that is shared between that person's descendants and that person's non-descendant relatives. Needless to say, this must be done very carefully to ensure that matching DNA from other ancestral lines are not mistakenly included in the reconstructed kit.

My target here is my great-grandfather Hersch Pickholz, who was born in east Galicia in about 1853 and died in Pittsburgh in 1931. His parents are Isak Fischel Pikholz - whose parents and siblings are unknown - and Rivka Feige Pikholz - whose parents and (at least  some) siblings we know. We have DNA tests for three of Hersch's four surviving grandchildren and twelve great-grandchildren.

Hersch Pikholz
My great-grandfather Hersch Pickholz has two sisters and two half sisters (from his mother) who have descendants who have tested for our project, plus one brother whose one identified grandchildren were killed in Europe.

Hersch Pikholz, his tested descendants, two sisters, two half sisters, parents and known grandparents

So this gives us fourteen descendants and nine non-descendant relatives, for a total - after some adjustments - of 1947.2 cM. To this I added the seven great-great-grandchildren of Hersch's mother's three brothers.
The addition of these seven non-descendant relatives, brings Hersh's Lazarus kit to 2558.9 cM. But it's not that simple. There is a Mordecai Pikholz who is undoubtedly related to both Hersch's father Isak Fischel and to Hersch's grandfather Isak Josef, but we have no idea how. Some of his descendants are already in the picture, as you can see in red below.

So Charlie's mother has one grandparent from Isak Josef and one from Mordecai. The same for Judy's father. Leonora's has four Pikholz grandparents, two from each side, and one of those - Cirl - has one parent from each side. But I am OK with this because as far as Hersch is concerned, Charlie, Leonora and Judy are all non-descendant relatives, therefore good for his Lazarus kit.

But as long as I have introduced Mordecai, I figured I may as well include his other three sons, each of whom has one descendant who has tested. Adding these three - Barbara,  Dalia and Lloyd - bring the total of Hersch's kit to 2742.4 cM.

Rivka Feige Pikholz, the mother of Hersch
At some point, while preparing the Lazarus talk, I realized that I already had enough information in hand to do a nice Lazarus kit for Hersch's mother Rivka Feige. So just for fun, I did. The twenty-three who tested in the chart at the top are all her descendants and the seven in the second chart are all her brothers' descendants. In this case, I decided to omit Barbara, Dalia and Lloyd.

Rivka Feige's test kit was a respectable 2189.5 cM. (Had I included Barbara, Dalia and Lloyd, it would have been 2708.9 cM. This is a large difference, which seemed to me to justify leaving them out.)

I then compared the two kits, Rivka Feige and Hersch, mother and son. Keep in mind that I have not included anyone who is known to be related to Hersch ONLY through his father Isak Fischel, and in fact it is highly unlikely that there is anyone who fits that category, since all these Pikholz are clearly related, closely. Not through some structural Jewish endogamy, but because these close cousins were marrying each other in the current generations.

The match between the Lazarus kits of Rivka Feige and Hersch is 1357.9 cM. That means that fully half of Hersch's Lazarus kit (2742.4 cM) does NOT come from matches to his mother. But we tested no one who is exclusively from his father's family. Even if we grant that Barbara, Dalia and Lloyd might be in that category, they only added less than 200 cM to Hersch's Lazarus kit.

This is the power of endogamy.

Again, let me remind you, dear reader, that this mother-son comparison was not the purpose of the Lazarus presentation. It was something that I looked at "just for fun" much as I looked at Hersch's predicted eye color just for fun. We have no photographs of Hersch Pikholz, even though he lived in Pittsburgh for nearly thirty years. Certainly nothing showing his eye color. But my grandmother kept waiting for a red-head grandchild, because Hersch had a red beard. This is what GEDmatch said about his eye color. Just for fun.
Last week, I mentioned my plans for a trip to the US before RootsTech. I am available for presentations then - in particular the full "'s Lazarus Tool As It Applies to Two Kinds of Endogamy." #PROGRAMCHAIRS