FTDNA vs. GEDmatch

My first thirty-one matches on FTDNA's Family Finder are known relatives. This is number thirty-two.

Thanks to Leah for permitting me to cite her here by name.

We share 170 cM which looks promising enough that FTDNA suggests that we may be second-third cousins, though I know that is highly unlikely. Our longest segment is only 8 cM, which pretty much disqualifies this as a match at all. It means that we have at least twenty-one segments of 8 cM or smaller, many of which are undoubtedly false - not indicative of any relationship whatsoever - with the others perhaps reflecting some very distant common ancestors.

It looks even more obscure when I look for Leah among the matches of my five siblings. Two of my sisters do not show up as matches at all. The other two and my brother are estimated by FTDNA to be Leah's fifth-remote cousins.

But since I had already begun looking at the match, I asked Leah about uploading to GEDmatch/Genesis. Genesis tells me that Leah and I share 29.8 cM, quite a drop-off from FTDNA's 170. It is no surprise that there is a difference, FTDNA counts very small segments and GEDmatch does not. Those very small segments are not worth much, so advantage GEDmatch.

But there are differences in the algorithms, as well, and I thought it would be useful to revisit that here. For that I looked at my five Kwoczka cousins, descendants of my great-grandmother's two brothers. I compared them to my father's brother, as I myself match only four of the five on Family Finder.

The adjustment of the FTDNA threshold from 1 cM to 7 cM lowered the Kwoczka cousins' matches with Uncle Bob by 73-91 cM. Leah's matches with me went down by 162 (!) cM, about twice as much.

The total matches on GEDmatch are significantly larger than the 7 cM FTDNA matches. I think this has to do with the algorithms.

The Genesis matches are somewhere in between - smaller than the original GEDmatch but larger than FTDNA.

One of the oddities here is the longest segment. There might be some algorithm issue, but there should be no threshold issue. For three of the Kwoczka cousins, there is no significant difference between FTDNA and GEDmatch. For the match between Uncle Bob and Cousin Br, the longest segment according to FTDNA goes from 24,778,179 to 112,771,988. The GEDmatch numbers are very close to these, though the length in cM at FTDNA is 20% greater than at GEDmatch.

The more significant difference is between GEDmatch and Genesis. They start and end at about the same places, but Genesis has a break in the middle, such that GEDmatch gives us a length of 70.1 cM while Genesis has two segments totalling 66.7 cM - nearly the same.

The longest segment between Uncle Bob and Be is different. FTDNA and GEDmatch show near identical results, but Genesis is about twenty-five percent lower. But it is not because of a gap in the segment.

Here the beginning of the segment is significantly different.

I long ago decided that I don't really need to know why these results are different from one company to another. I just have to choose one and work with it. So now that GEDmatch has moved on from the old standard, Genesis is where it's at.


Housekeeping notes 

Order here.
European Jews have always married mainly within the tribe. Whether our numbers five hundred years ago in Europe were four hundred or four hundred thousand, the pool was limited. As a result, the members of the tribe today are all related to one another, multiple times.  This phenomenon, known as endogamy, makes Jewish genetic genealogy very difficult, often impossible. There is a similar phenomenon in some other population groups.

I was convinced that this brick wall is not as impenetrable as it seems, at least in some circumstances.

I believe that this book demonstrates that I was correct.

When I decided I wanted to write a book, I was not sure if I wanted to write a “How to” book or a “How I did it” book. The decision was dictated by the facts in the field. Different family structures, widely different numbers of living family members, and other similar factors dictated that writing “How to” would be irrelevant for most researchers.

“How I did it” is more likely to be helpful to the research community and more likely to instill the confidence necessary for such a project.

It is my hope that this book will encourage and inspire other researchers of their European Jewish families and other endogamous populations to say “I can do this!”

Politzer

Customers of Family Tree DNA are familiar with the match alerts we get from time to time, whether our own kits or the kits of members of our projects.

As I manage over a hundred kits, I am not about to stop what I am doing to look at these every time I receive one and in any case, I want to see how a match fits not just with me  but with other family members including those not close enough to warrant an alert. So nearly two years ago, I decided to look at all the new matches across my family members every few months. Then I write to the ones that look interesting and ask them to upload to GEDmatch to see if these matches are on shared segments.

Usually nothing much comes of it. Even when the DNA points to a very specific portion of my family, the match usually doesn't know any of my surnames or even my geography.

Last week I prepared the matches for the past four months and Sunday I sent out messages to the scores of matches who looked even a little bit promising. So let me tell you about Cynthia, who happens to be the wife of a fellow I actually know.

So I asked her to register for GEDmatch/Genesis and after it batched I looked at her top 20,000 matches using the Tier1 one-to-many search. She matches seventy-eight of my kits and I did some chromosome browsers to see how her matches line up in family groups. As usual I was looking for segments of over 10 centiMorgans with multiple meaningful matches with my families.

On chromosome 3, she matches seven of us - four of my parents' children, one first cousin and two second cousins, all pointing to my maternal grandfather's side. All we have there are the surnames Gordon and Kugel. And it was a small match anyway, so probably from a pre-1800 common ancestor.

Chromosome 5 showed a 12 cM match with a pair of second cousins in the Nachman Pikholz branch of the family. Not much with that either - but if Cynthia had the relevant surnames, it could have been nice.

Chromosome 6 had two segments of minor interest - one with some second and fourth Pikholz cousins of mine and another with one first cousin and three second cousins on my maternal grandmother's Rosenbloom side. Here too, we have no other surnames, but we do know that the
family lived in Borisov (Belarus) for at least half of the 1800s.

Both chromosomes 16 and 20 brought matches with small groups of my third and forth cousins on

the Pikholz side.

Chromosome 22 has seven descendants of my Pikholz great-great-grandparents. Both of these ancestors are Pikholz.

Then there is the X, chromosome 23. The relevant matches look like this.

The four nearly identical matches belong to two of my sisters, my father's brother and my fourth cousin Lydia. They all triangulate, so they are all from a common ancestor.

This cannot be from my grandfather, because Uncle Bob gets no X from his father. So we know it's my grandmother's side. So given Lydia, who is part of my grandmother's paternal grandmother's Zelinka family, how exactly does this fit together and who is the candidate for the common ancestor?

Uncle Bob is a third cousin to Lydia's mother
so we and Lydia are fourth cousins.

Nathan / Nahum Zeinka's fallen gravestone

Our most recent common ancestral couple are Isaak and Sari Zelinka, who were born in the mid-1780s. But Lydia's second-great-grandfather Nathan Zelinka received no X from his father, the source of the match between Lydia and Uncle Bob must be from Sari, Isaak Zeinka's wife.

Nearly two years ago, Uncle Bob's daughter Linda and I were in Slovakia, together with our fifth cousin on the Zelinka side, Cyndi and while in Zilina we met Lydia. In the course of taking down her family information, I asked if she knows anything about our third-great-grandmother Sari. Lydia said that she understood that her surname is Politzer. This made sense to me because many years ago, my grandmother had told me that her father was related somehow to Joseph Pulitzer - he of the prize. - but she had no idea how. I have tentatively recorded Sari as Politzer, pending some kind of actual documentation.

So last year, Lydia gave our third-great-grandmother a name and perhaps a family and now we have an actual bit of her DNA.

(Note, I could have seen this with an analysis of Lydia, having nothing to do with Cynthia, but I didn't - so I can thank Cynthia for that.

Caveat - it is theoretically possible that the segment comes from my grandmother's MOTHER's side and that Lydia has some unknown ancestry in Hungary, but I consider this to be a vanishingly small possibility.

The Matching Segments tool on GEDmatch does not include the x chromosome, but on Genesis it does. They call it "Segment Search" and it is on Tier1. There are about three dozen people who share that match with both Uncle Bob and Lydia and I suppose I should write to them. Maybe something else will turn up.

(What I don't understand is why Uncle Bob and Lydia do not show up on Cynthia's Segment Search. I'll have to speak to GEDmatch about that.)

Housekeeping notes 

Order here.
European Jews have always married mainly within the tribe. Whether our numbers five hundred years ago in Europe were four hundred or four hundred thousand, the pool was limited. As a result, the members of the tribe today are all related to one another, multiple times.  This phenomenon, known as endogamy, makes Jewish genetic genealogy very difficult, often impossible. There is a similar phenomenon in some other population groups.

I was convinced that this brick wall is not as impenetrable as it seems, at least in some circumstances.

I believe that this book demonstrates that I was correct.

When I decided I wanted to write a book, I was not sure if I wanted to write a “How to” book or a “How I did it” book. The decision was dictated by the facts in the field. Different family structures, widely different numbers of living family members, and other similar factors dictated that writing “How to” would be irrelevant for most researchers.

“How I did it” is more likely to be helpful to the research community and more likely to instill the confidence necessary for such a project.

It is my hope that this book will encourage and inspire other researchers of their European Jewish families and other endogamous populations to say “I can do this!”

Cheryl - A GEDmatch Case Study - Part Two

Cheryl matches my families
A few days ago, I wrote about my neighbor Eric whose wife Cheryl has a promising match on GEDmatch with a Skalat Pikholz descendant named Gene. Aside from Gene, Cheryl has a number of other matches with my families.

There are five segments of interest, none very close, but together they may be useful, both for Cheryl herself and as examples of how to use GEDmatch.

Eric was here for a little over an hour, so after we looked at Gene, we went straight to the old reliable one-to-many search which looks at Cheryl's top 2000 matches. I was looking for segments of ten or more centiMorgans where Cheryl has multiple matches in my families. Segments smaller than ten cM may be real, but are certainly too far away to be useful for families such as ours where we have few surnames or records before 1800. And I use multiple matches because I want some evidence that the match is from "our side" and not from the other side of some second, third or fourth cousin.

The five segments of interest
On chromosome 1, Cheryl has about 11 cM with Aunt Betty and Uncle Bob, my father's sister and brother. This is not a large segment and we cannot tell whether this is on my grandfather's side or my grandmother's. And given that, the common ancestor probably lived well before 1800.

On chromosome 5, Cheryl matches my brother, one of my sisters and me on a segment of 10.7 cM. No cousins on either side, so this match could come from anywhere. And it is not large.

On chromosome 9, Cheryl matches my brother, three of my sisters, me and my second cousin Roz, on my father's father's side, with a segment of about 12 cM, plus a nearly-adjacent segment of about 5.6 cM. We all match each other, so we have triangulation. So this segment comes from either my grandfather's Pikholz father or his Kwoczka/Pollak mother, all from the Tarnopol area of east Galicia.

On chromosome 11, Cheryl has a segment of about 15 cM with two of my second cousins on my mother's side. One is Beth, whose grandfather is my grandmother's brother and one is Liya whose grandmother is my grandmother's sister. They match each other, so we have triangulation. My grandmother's descendants do not appear here, nor do Beth and Liya's two first cousins. Is there something here? Maybe. But we have only one surname in my grandmother's family - Rosenbloom from Borisov in Belarus.

Finally, on the X, Cheryl has 20.5 cM with Aunt Betty and 14.9 cM on the same segment with my cousin Roz. They triangulate, so this is a real match. Aunt Betty could not have gotten the X from her father's father and Roz would not be expected to match Aunt Betty's mother, so the match must be from the Kwoczka/Pollak side. We cannot know if it is from the same common ancestor as the segment on chromosome 9, but the possibility is intriguing.

Digging deeper with a better way
At this point, my discussion of last week on the GEDmatch Tier1 one-to-one kicks in. I told Eric that after he signs up for Tier1, he should see if any of Cheryl's matches beyond the initial 2000 can tell us more about these five segments.

But there is a better way. GEDmatch has a tool called "Multiple Kit Analysis." It is marked as NEW, but it has been around for quite awhile. And it is not a Tier1 tool, so it is freely available.

In the Multiple Kit Analysis there are two tabs. Choose the one on the right: "Manual Kit Selection/Entry." If I enter Cheryl's GEDmatch kit in the first box ("Kit 1"), I can compare her to all the kits I enter in the subsequent boxes, whether or not they are in Cheryl's first 2000 matches. For instance, if I enter all the kits from my mother's side, I can see if anyone besides Beth and Liya match Cheryl on the segment on chromosome 11. But entering all those kits by hand is tedious and prone to error. Here I have a short cut that Eric cannot use without knowing the GEDmatch numbers for all my relevant kits.

I use a free program called ShortKeys which I have set up to fill out this form for each of my families. When I did that for my Borisov family (the ShortKey code includes many Borisov residents who are not specifically related to me), I got one more second cousin on the segment with Beth and Liya - Liya's first cousin Lydia. This strengthens this segment as a useful connection between Cheryl and my grandmother's family beyond what we had on the basic one-to-many. Eric could have done this using the Tier1 one-to-many but I find this easier for matches with my families.

Cheryl matches Beth, Lydia and Liya together

That same search gave me another bit of information regarding my mother's side. On chromosome 5, we see the three 10.7 cM matches that I mentioned above - my brother, one sister and me. But we also have 12 cM with my first cousin Mike (line 5), on my mother's side. He triangulates with us here, so this is real.

There are no second cousins on the segment so we don't know which of my mother's sides is represented here.

Uncle Bob, Aunt Betty and Pinchas
line up together on chromosome 1

I also did the Multiple Kit Analysis for the other three segments - the ones that show matches between Cheryl and my father's side. On chromosome 1, where Cheryl's one-to-many showed a match with Aunt Betty and Uncle Bob, the Multiple Kit Analysis gave us one more name: my third cousin Pinchas. Pinchas' great-grandfather is the brother of my great-grandmother Jutte Leah Kwoczka, whose mother is a Pollak.

This match triangulates so it clearly comes from the Kwoczka/Pollak side - not Pikholz and not my grandmother's Hungarian/Slovakian families.

Chromosome 9 showed us nothing new, so we have only the original matches with my second cousin Roz. Maybe Pikholz, maybe Kwoczka/Pollak.

Five of my parents' children and our second cousin Roz (on line 6). Not large but definitely my father's father's side.

Chromosome 23, the X, gave us two new matches - Rhoda and Terry.

The two large yellow matches (20.5 cM) are Aunt Betty and Roz' first cousin Rhoda. The first green match is my second cousin Terry, with 15.2 cM. The second green match is Roz, with 14.9 cM. They all triangulate. This is clearly a Kwoczka/Pollak match.

This X match and the Kwoczka/Pollak match on chromosome 1 may or may not be from the same ancestral source.

The ball is now in Eric's court. He can do Matching Segments and write to others who share these matches. But perhaps more important, he can get some of Cheryl's first and second cousins to test, so he can see which of Cheryl's ancestors provided these segments.

When he comes back to me, I'll report it here.

Housekeeping notes
I shall be speaking, in Hebrew, for the Rishon LeZion branch of the Israel Genealogical Society on Monday, 14 January at 7 PM at the Rishon LeZion Museum, 2 Ahad Haam Street. This is not a DNA presentation, though there are a few DNA references. The topic is

מֵעֵבֶר לְסָפֵק סָבִיר

מה שיודעים, לעומת מה שאפשר להוכיח

BEYOND A REASONABLE DOUBT

What We Know vs. What We Can Prove

(These) GEDmatch Inconsistencies - SOLVED

The problem
Last week I reported in this space about a problem I was having with GEDmatch. A match named Lauren had eleven matches with my families (using the one-to-many search) which her father George did not share, but were definitely not from her mother. When I dug deeper, I saw that George in fact matched all eleven when I used the one-to-one search.

I sent a link to that blog to the GEDmatch team and gave them the relevant kit numbers. Since then, I have been going back and forth with John Olson and I am pleased to report that we have a solution which John asked me to pass on to my readers.

How the basic one-to-many works
As we know, most of us endogamous folk have a few tens of thousands of matches on GEDmatch, but they only show the first 2000. (Early GEDmatch showed only 1500 matches, which proved inadequate.) "First" in this case means the lowest numbers in the "autosomal generations" column, which is the default sorting key. Other matches are available on the one-to-one searches, but when you manage a large number of kits, as I do, looking for those one-to-ones is not practical.

Most of my kits are given a name beginning with "*0Pikh..." so they will all sort together, near the top and I had always understood that when I sorted on the name column, they would show the first 2000 names from the entire match list. It turns out that this is not the case. The first 2000 matches are fixed and any sorting works only within that set of matches.

In this specific case, George's first 2000 matches go up to 3.9 generations while Lauren's go up to 4.5 generations.

Here are the last four matches of each of them:

George's matches with the eleven "missing" kits are all further than the last of the 3.9 generations that are displayed.

This may be a problem peculiar to endogamous populations where the number of matches is huge. Perhaps non-endogamous populations will have in their first 2000, matches that go to 5.0 generations or more.

And George may have more matches under 4.0 than most endogamous kits. But I see that I also go up to 3.9 generations and my two first cousins (not siblings) with one Jewish parent, both go to 4.4 generations. Frankly, 3.9 generations is not enough, nor is 4.4, so we need a way to enlarge the match list.

The solution

The way to solve this is by using the Tier1 one-to-many. Tier1 is a set of seven (at last count) GEDmatch tools which are available to those who make a donation to GEDmatch. This is not a subscription. You can do a single month for $10 each time you need it. (I think they deserve ten dollars a month just on general principle so am always signed in to Tier1.)

The Tier1 one-to-many gives you a choice among seven match limits, from a low of 500 up to 100,000. Both George and I have bit more than 40,000. My two first cousins with one non-Jewish parent have about 29,000 and 33,500 total matches. And it covers all the matches, with the same sorting capacity that I have gotten used to.

The 100,000 match limit search took me less than a minute, so it's not terribly burdensome.

So henceforth all my one-to-many searches will be with Tier1.
"ONE-TO-MANY" IS DEAD. LONG LIVE "ONE-TO-MANY!"

The Descendants of Chana Chaje Pikholz

Background
I last wrote about the family of Mordecai Pikholz (~1805-1864) and his relationship to Izak Fischel Pikholz, my second-great-grandfather, about two months ago - here and here. I am pretty sure that they are brothers but I have nothing conclusive.

Here is the structure as we know it.

The purple-shaded area is the family of Chana Chaje.
People in yellow in parentheses have tested. For instance Dalia, a descendant of Chaim Yaakov.
Judy, Charlie and Leonora are also descended from Isak Josef on the top left.

In my posts two months ago, I discussed the Family Finder results of Ruth (at the bottom in green). We now have results for her first cousin Dana and their third cousin Moshe. (Ruth and Dana are also second cousins  as their non-Pikholz grandmothers. are sisters.)

Mordecai's eldest daughter Chana Chaje (~1823-1896) was married to a man named Eliezer (~1822-1878). We do not know his surname but he was a Levi, a family tradition backed by Moshe's Y-37 test. He may have had a generic Levite surname such as Segal or Halevi, or it may have been something else. In any event, the family was known as Pikholz, including Eliezer himself as we see in his death record, where he is listed by the nickname "Leiser."

Moshe's autosomal matches
Moshe has interesting segments with multiple matches on five chromosomes.

On chromosome 4 he has matches of nearly 11 cM with descendants of Rivka Feige, my g-g-gm, from her first husband Gabriel Riss. This is pretty clearly a Riss segment. Of course we have no idea who Moshe's common ancestor with the Riss family might be.

On chromosome 11, Moshe has a segment of nearly 29 cM with Ruth, 17-20 cM with Charlie and Nan and 12 cM with Dana. Charlie is a descendant of both Mordecai and Izak Josef, while Nan is a decendant of only Izak Josef. Izak Josef has no Y-DNA descendants, so we can tie him to Mordecai only through autosomal match such as this.

On chromosome 13, Moshe has a segment of 31.5 cM with Ruth and 16.3 cM with Dana. I would guess that this segment came from Eliezer the Levi, Chana Chaje's husband, rather than from Mordecai Pikholz or his wife Taube. This makes it less likely that Eliezer is closely related to the family in some other way, such as through Mordecai's wife Taube.

On chromosome 18, Moshe has 43 cM with Leonora and 42 cM with Dana on largely overlapping segments. (Leonora and Dana have a match on that segment of 38 cM, with a smaller segment almost immediately adjacent.) These are three mutual third cousins. Lara Diamond's Ashkenazic Shared DNA Survey shows third cousins sharing a longest segment anywhere from zero to 91 cM, with an average of 26.66 cM. (Her sample size is 397.) So this layman thinks that a single segment of over 40 cM is large and a share of that size among three mutual third cousins is fairly rare. This segment is probably from Eliezer the Levi.

Finally on chromosome 20, Moshe has a segment with Leonora of 60 cM including nearly 57 cM with Dalia.

The segment also includes matches of 24-32 cM with my cousins Fred and Herb, Barbara and Dana - and smaller segments with three cousins who are strictly Izak Josef descendants and my cousin Roz. These matches add weight to the connected nature of the families of Mordecai and Izak Josef, but without shedding much light.

I also ran Moshe's prominent segments on the Matching Segments Tool at GEDmatch and found quite a few non-Pikholz on most of them. I will probably write to those above whatever threshhold I set - perhaps 25 cM - and if the past is any indication, those who bother to respond will tell me that they don't know anything. But if even one can add to our knowledge, it is worth the effort.

Dana's autosomal matches
I discussed Ruth's matches previously but since she and Dana are so closely related (both first and second cousins) I cannot discuss Dana without mentioning Ruth.

On chromosome 4, Dana and Ruth have a matching segment of nearly 40 cM. Leonora matches a bit more than half of that segment. On the other end of that segment, Judy has a

match of nearly 20 cM, my father's sister has a match on just over 20 cM and my cousin Rhoda has a match of 12 cM. Those last three match Dana and Ruth either through Izak Josef or because Izak Fischel and Mordecai are brothers.

On chromosome 5, Dana has 27-28 cM with two of Izak Josef's descendants and 11 cM with one of my cousins. Ruth shares part of that. That is another segment shared by Mordecai and Izak Josef's descendants.

Looking further at chromosome 5, I saw two large-ish matches with strangers on the Matching Segments Tools.

Two strangers match this segment with Dana and Izak Josef descendants. I wrote to them.

Dana's matches on chromosomes 13 and 20 are covered by what I wrote about Moshe above.

On chromosome 18, Dana has the one large segment with Moshe and Leonora that I discussed above plus one more with Charlie of 25 cM together with smaller matches with Ruth and Nan.

The general overview
Dana's matches with the Isak Josef and Isak Fischel descendants are sronger than Moshe's but weaker than her close cousin Ruth's. My feeling is that the difference between Dana and Ruth is just the vagaries of DNA, while the difference between the two women and Moshe is real. Perhaps if Dana's brother tested, he would be closer to Ruth than Dana is. Perhaps if Moshe's sister tested, she might be closer to Dana and Ruth than Moshe is.

The one I really want to test is Esther, the granddaughter of Tema. She is one generation older than the other descendants of Chana Chaje, though she is chronolocally younger than some of them. Esther seems to have moved since my last contact with her.

Four years ago, I wrote about three or four marriages between the Pikholz family and the Zellermayers. I expect that there is something further here - perhaps Izak Josef's wife. I am not sure at this time how I might determine that.

64.2 centiMorgans

A few weeks ago, Beth Long - Hungarian researcher extraordinaire - asked me to join a project she was working on regarding a woman born during the Holocaust but has no idea who her parents are. More on this another time, perhaps with a guest blog by Beth herself.

But there is one corner of this project which warrants a spotlight now. One of my favorite soapboxes.

The woman - we'll call her the Holocaust Baby - did a DNA test at Ancestry and uploaded her results to GEDmatch where she found a number of matches of interest. Two of those - male first cousins to one another - match her in the 220-260 cM range. (All the DNA information cited here is based on GEDmatch on-to-one searches with the standard threshold of 7 cM. These do not include the X chromosome.) That is second cousin territory.

A third first cousin tested and his match is 336 cM.

There are several segments where these three cousins match the Holocaust Baby, particularly on chromosomes 7 and 8.

The first question was which side of these cousin is relevant, their grandmother's side or their grandfather's side. Beth tested two second cousins on their grandfather's side (orange) and their matches with the Holocaust Baby are less than 50 cM.

Wrong direction.

The connection with the Holocaust Baby must be on their grandmother's side. Beth built trees and went after the relatives.

The grandmother had a brother (green) and two of his grandchildren tested. One matches with 323 cM, also second cousin territory.

The other, with only 64.2 cM - well, who knows!

A second cousin once removed of the original three testers (in blue) is in the testing process.


The grandmother had a sister (pink) with a living grandson from her first husband and two great-grandchildren from her second. They would be second cousins and second cousins once removed to the original blue testers.

Here too, the sizes of the matches point to an as-yet-unidentified sibling of the blue grandmother, though 423 cM is high for a second cousin. But of course these Jewish families are subject to the vagaries of endogamy, where people are related multiple ways.

We have proceded beyond this and results there are not in, but that is not the point of this article. The green second cousin with the 64.2 cM match is way out of line with everyone else. I expected that he is not really a second cousin. The genetic father (or grandfather) is not who he is supposed to be.

But that is simple enough to confirm. We compared the 64.2 cM cousin to the rest of his known cousins, his green close cousins and the blue and pink second cousins..

At 64.2 cM he may not look like a second cousin to the Holocaust Baby, but he matches everyone else quite well. He has a particularly large match with his first cousin, at 1158.6 cM. So there is no misattributed paternity here. This man is a second cousin to the Holocaust Baby - at least as much of one as the the others with the "normal" matches..

Here is what Blaine Bettinger's Shared cM Project says about second cousins.

64.2 cM is way below the expected 213 cM for second cousins. It is below the 95th percentile which goes as low as 99 cM. Note that the pink cousin who matches the Holocaust Baby with 423 cM is also outside the 95th percentile, but in the other direction. And these two match each other within the norm.

So the lesson here is that norms are just that - norms. The ninety-fifth percentile still excludes five percent and five percent of the matches will be out there on the fringes. It is easy to say "This doesn't look like a good match." Easy - even lazy.

For this project it doesn't matter, but I would be curious to see what kind of match the Holocaust Baby would have with Mr 64.2's siblings, if he has any.

I have said this before. You have to test everyone. I expect I will find opportunities to say it again.

How Close Are We - GEDmatch and Known Matches

A few days ago, Liza Lizarraga called our attention on Facebook to a year-old blog about the "generations" column in the GEDmatch "one-to-many" results. In her blog GenGenAus, Cate Pearce tells us how the generations that GEDmatch shows us line up with her own reality. I had never seen this blog or any other form of this analysis.

Above are my own one-to-many matches with four people in my Pikholz project. I am not sure how I am related to them, but I call them "my fourth cousins". The first two are known to have multiple Pikholz ancestors, but the approximations that GEDmatch shows (in the red box) do not help much.

 
Yet some people want them to be useful - even definitive - and the occasional poster on Facebook or in discussion groups will ask "What does 4.7 generations mean, exactly?" Well, there is no "exactly" once you get past parent/child relationships. And beyond that, Cate shows us what her actual family matches look like:

Gen 2.3 1C1R (first cousins once removed)

Gen 2.5 1C1R (first cousins once removed) Again, this makes sense: my cousin is a generation older than me, his grandparents, which is 2 generations, are my great-grandparents, which is 3 generations. Therefore, the Gedmatch Generation is calculated as being between 2 and 3 = 2.5

Gen 2.6 1C1R (first cousins once removed) 2C (second cousins)

Gen 2.9 2C (second cousins)

Gen 3.0 2C (second cousins)
This is the ideal scenario, with the common shared ancestors for me and my match both being 3 generations back.

I figured it would be useful to do something similar for endogamous populations and felt that it would be more user-friendly to put it in a structure like Blaine Bettinger's Shared cM Project. So with Blaine's kind permission, I prepared an analysis of my 1184 known family relationships, shown in the chart below. (There are more data points on the way, waiting to get a few more kits onto GEDmatch.)

This chart has no claim on precision. The averages do not include those matches which do not show in the traditional one-to-many search on GEDmatch, what we call "the zeroes."

Some do not show up because they do not meet the conditions for a match. Some are good matches but have only a single segment and for some reason GEDmatch does not display these. Some are matches but do not fit into the 2000-match limit which GEDmatch imposes.

Multiple known relationships are listed by the closest one and there is no special acknowledgement of my double second cousins.

I also show the sample size, which does not include the "zeroes."

I would be really pleased to have some more data. Anyone in the endogamous community who wishes to join in can download the simple Excel form at www.pikholz.org/GenerationsForm.xlsx. Needless to say, privacy will be maintained. And you do not need to identify the specific matches, just the relationships.

        

Housekeeping notes

I just took DNA from the wife of my boss forty years ago. She told me back then that she is a Pikholz descendant and now I know that her third-great-grandparents are Mordecai Pikholz and his wife Taube. I still don't know how Mordecai and my second-great-grandfather Isak Fischel are connected. Maybe brothers. I have been after her to give me DNA for years.

I'd be pleased to see any of you at the following three events.

30 April 2018, 7:00 – Jewish SIG of the St. Louis Genealogical Society, Holocaust Museum & Learning Center Theater, 12 Millstone Drive, St Louis Missouri
Using Genetics for Genealogy Research
(Lessons in Jewish DNA – One Man’s Successes and What He Learned On the Journey)

2 May 2018, 6:00 – Jewish Genealogical Society of Kansas City, Johnson County Central Resource Library, Carmack Room, 9875 West 87th Street, Overland Park Kansas
Lessons in Jewish DNA – One Man’s Successes and What He Learned On the Journey

8 May 2018, 7:00 – Youngstown Area Jewish Federation and the Mahoning County Chapter of the Ohio Genealogical Society,  Jewish Community Center of Youngstown, 505 Gypsy Lane, Youngstown Ohio
Why Did My Father Know That His Grandfather Had An Uncle Selig?
(because genealogy is more than names and dates) 

JRI-Poland still needs considerable funds for the new indexing projects. Among the towns I am responsible for, Skalat and Skole are far from their goals, but Rozdol, Komarno, Zbarazh and Podkamen need funds as well. See instructions for donations here - and don't forget to say which projects you are supporting. And let me know what you have contributed.

Tara, Her Paternal Grandmother, My Cousin Kay and Others

This is the second of at least three posts regarding my families' matches with a young woman named Tara in Toronto. I discussed her matches earlier and now we have results from both her mother and her paternal grandmother. I will discuss her mother's matches in a few days, but there is something else I wish to address first. (My mother used to say that "a few days" means less than a week. No promises.)

Chromosome 8
Using the GEDmatch basic one-to-many tool, on chromosome 8, Tara matches my brother and my sisters Amy and Jean on identical segments of about 12.6 cM, the range being 96,812,006 - 107,594,161.  My sister Sarajoy is on the same segment with 9.8 cM that ends in the same place as the other three, but starts a bit later.

The triangulation is a bit odd as everyone matches on the appropriate segments except Dan and Sarajoy. It is not clear to me how that happens, but that is not what I am getting at.

I then ran the Matching Segments Tool for Tara and found a surprise. My first cousin Kay (our mothers are sisters) is on the same segment almost exactly matching Dan, Jean and Amy. But she hadn't been on the regular one-to-many. And the fancy Tier1 one-to-many has the same result as the old reliable.

The Matching Segments result for Tara is here on the right.

Kay triangulates with my brother and all three sisters on that segment of chromosome 8.


Kay should show up as a match to Tara on the one-to-manys and she doesn't. Something odd is happening at GEDmatch. Perhaps it is because this is the only segment on the twenty-two chromosomes where Tara and Kay match, though I don't know why that should matter..

So now Tara has the results for her paternal grandmother, whom we shall call Ida. Ida matches my brother, my three sisters and Kay on the basic one-to-many slightly more than does Tara. (Perhaps the fact that Ida has two segments with Kay comes into play here.) But Ida does not match Kay on the Tier1 one-to-many. On the other hand, Kay shows up in Ida's Matching Segment results but Sarajoy does not.

There is a lot of inconsistency here and it all seems to lie at the door of GEDmatch. If nothing else, it appears that we must check both one-to-many tools as well as the Matching Segments every time we look at someone new.

But we do know that we have at least one common ancestor with Tara on my mother's side of the family. Unfortunately since none of my second cousins match Tara on this segemnt of chromosome 8, we cannot break it down any further.

Chromosome 23
Another GEDmatch mystery involving Tara and Ida is on chromosome 23, the X.

Tara has  a segment of about 10.5 cM with my sisters Sarajoy and Jean, together with my second cousin Ruth on my mother's father's Gordon/Kugel side.

Ida has Sarajoy and Jean on that same segment using the regular one-to-many - and Kay as well - but not Ruth. The four of them all triangulate so they should all match both Tara and Ida. On the Tier1 one-to-many, neither Kay no Ruth appears. On the Matching Segments tool, Ida matches Jean and Kay, but not Sarajoy.

My feelings about GEDmatch are often just like my feelings about my children. I love them, but I don't always understand them.

There will be more about Tara's matches "in a few days."