Thursday, December 4, 2014

Small But Meaningful Segments on DNA

Some short but meaningful segments, all of them about DNA.

(Note: There is now an email sign-up box, here on the right. Thanks to genealogy blogger Lara Diamond for showing me how to do that.)

Lazerizing my mother
Recreating my father's DNA using Lazerus last week was easy. I mean, he has three descendants who have tested, both his brother and his sister and one of his two living fIrst cousins. I didn't need to use the first cousins once removed and the second cousins and I still got about 62% of his 22-chromosome set.

My mother is another story. The same three descendants for Group 1, two of my sisters and I. But my mother's two brothers and two sisters predeceased her and the first yahrzeit of her last first cousin is this Wednesday evening. To top that off, Mother has only one niece and
one nephew we can work with and the nephew has not tested. We do have two of my second cousins on my grandfather's side who have tested. One on my grandmother's side has tested but I cannot get her onto GEDmatch. So all we have for Group 2 are Kay, Ruth and Judy - the last two first cousins to one another.

The resulting kit is about 36.6% of a full set of 23 chromosomes - including the X - if I have the math right. I am quite sure that we have some endogamous segments here from Ruth's father and probably from Ruth and Judy's grandfather, so maybe it's just 32% or 28 %. But since I am not planning on doing anything with my mother's kit for now, it doesn't matter.

I am just trying to get a handle on how many people we need in Group 1 and Group 2 (and how close) in order to get some meaningful results. GEDmatch will not do "one-to-many" comparisons with the Lazerus kit unless it gets over a certain threshhold and Mother's kit passes that test.

Meantime another of my sisters has ordered a test.

Matching my mother-in-law
Tuesday evening Jerusalem time, I posted the following on the Facebook pages International Society of Genetic Genealogy (ISOGG) and Tracing the Tribe, as well as my own timeline.

It provoked quite a few "Likes" and comments.

My point was not to be entertaining, though it certainly got its share of yuks (and some yucks).

My point was to say something about endogamy and how and why I do what I do with autosomal DNA.

I would guess that of those using DNA for recent genealogy (not, for instance, deep ancestry or medical matters), almost all are either looking for new relatives in hopes of working their ancestry back additional generations or are looking for specific unknown individuals, as in cases of adoption and abandonment.

The problem with Jews using DNA to look for new relatives is that when you get right down to it, we are all related, very possibly in the last fifteen-twenty generations and often many fewer.

We keep marrying withing the closed tribe and we share many ancestors, not only with others but with ourselves. So when someone shows up as a suggested fourth cousin (on average about 50 cM of matching DNA), the relationship is usually composed of multiple incidents of more distant cousinhood.  Sixth, seventh and eighth cousins share on average12.5 cM, 6.25 cM and 3.125 cM so there are many ways to use small numbers to build to the 50 cM that makes it look like fourth cousins.

This is not as much of an issue with close cousins. Second cousins share an average of 200 cM, so some distant cousinhoods floating around in the background are part of the margin of error and don't really affect the larger number.

I am not looking for new relatives, nor do I have specific missing fathers or grandfathers to look for. I won't say that what I am doing is unique, but I can say that no one I know is doing it. 

My Pikholz research is single-surname. I have a number of Pikholz lines that go back to 1800-1830, three with pre-1800 patriarchs. I also have a few lines that only go back to the mid- or late-1800s because the name of the partriarch or matriarch is too common to identify further. I am using DNA to figure out how those families connect to one another back then.

Although I am still on the trail of documented proof, I have reduced the number of "free-standing" Pikholz families from Skalat by at least two and have laid the groundwork for at least four more, pending tests that are either in process or in begging-mode. I have also disproven at least two putative connections, when DNA did not show the expected results, (and not due to "false fathers").

I discussed some of that recently here and here, for instance.

This works. Slowly and carefully. Trying not to jump to conclusions. Doing my best to remain relatively free of endogamy.

Yes we are all related. But some of us are more related than others. I think I can demonstrate it. (See "Moshe Hersch" below.)

But back to my mother-in-law
Awhile back, I decided to get a DNA sample from my wife's mother, since she is the last of her siblings and on her father's side, the last of the cousins. I figured some day I might have reason to work on her family and who knows if she will be here by then.

I had no intention of doing anything but skimming the results, for now.

But her results showed matches with seven of the nine descendants of my great-grandparents, four of whom including Aunt Betty and my sister Amy are suggested third-fifth cousins. On the other hand, my sister Sarajoy is among the missing. She also matches both Kwoczka cousins, from my g-gm's family.

My mother-in-law also has remote matches with eleven other Pikholz descendants, including the putative descendant of Uncle Selig. Also Jane, who looks to be quite close to my own family.

So this really does seem focused on my personal family, probably from the Kwoczka side. She does not match any of my four first and second cousins on my mother's side.

My mother-in-law's mother was born in Przasnysz Poland and her father's family is from Kurima Slovakia. I am curious which of her sides is connected to my father's people, so I wrote to some of her first cousins on her mother's side and first cousins once and twice removed on her father's side, asking them to test. We'll see how that goes. The first three have agreed to test..

I have no idea what I am getting into with this.

Meantime, I'll let this exchange speak for itself.

Moshe Hersch
Two posts ago, I wrote about the second cousins Charles and Leonora, whose great-grandmother Sara Pikholz (~1847-1887) is the daughter of Moshe Hersch. I also wrote that the second cousins Jane and Nan are the great-granddaughters of Berish (1837-1918), whose father is also Moshe Hersch.

I suggested that these two Moshe Hersch may be the same person, which would mean that Charles and Leonora are third cousins of Jane and Nan.

At the time, we had test results from Jane, Leonora and Charles. Nan and her two children had submitted Family Finder tests. Nan's daughter's results just came in.
I couldn't have hoped for better than this
And the chromosomes look very good - see the nicely triangulated bits on 2, 16 and 20. Nan's results can only make this better.
Nonetheless, there are two things that bother me here. First, if Charles is indeed a third cousin of Jane and Nan, then their parents are second cousins. So why was there no known contact between Charles' mother in Newark and the others in the Philadelphia area either as part of the 1939 immigration or afterwards? I do not think that Charles' mother would have been closer to Sam Marenus (who assisted with her immigration) than to Jane and Nan's family. This does not necessarily indicate a problem with the "one Moshe Hersch" theory, but it does raise a small doubt.

The other is the given names. Berish has children named Olga (Alte), Anna (Chana), Fannie (??) and Odessa-born Vodolya Volodya* (Zev/Wolf). Sara, Berisch's putative sister, had Josie, Perl, Osaias, Leisor, Jenta and Taube. I would have expected at least a few names to appear in both families. Again, it proves nothing, but it makes me uncomfortable.

Small segments
In recent days, there has been quite a bit of very lively discussion on Facebook on the value of small segments of DNA in evaluating matches. The consensus is, and has loing been, that small segments are not really indicative of inherited DNA in any meaningful sense. There are, of course, differences of opinion about what size segments should be ignored because of their smallness.

Blaine Bettinger responded to the debate with a major article, full of numbers and graphs. I have not yet read it but I understand that he presents alot of statistics about the likelihood of small segments being useful and about what exactly is a  small segment.

The article has prompted a new Facebook discussion about the article itself.

It is my nature to distrust rules that put everything into a single category and that's how I feel about small segments. Sometimes they are meaningful and useful, sometimes not.

When I reconstructed my father's DNA using Lazerus (described last week in Genes From My Father), I happily accepted all small segments of whatever size because those small segments were in the DNA of at least one of his children and at least one of his brother/sister/first cousin. If I have a particular small segment, I must have received it from my parents. If my father's brother (or sister) has it as well, then it is eminently clear to me that I got it from my father and that it came to him and his brother from my grandfather. And it is not reasonable to say that a sliver of that small segment might have come from my mother, because my father's people share it.

Whether that segment came down unchanged and intact from one of my great-grandparents can be a matter of legitimate debate. Whether it came unchanged and intact from someone two-three generations further back can be a matter of legitimate doubt.

That's my story and I'm sticking to it.

Housekeeping notes
Seven Eight Pikholz descendants, all from Skalat, have ordered Family Finder tests in the last week.

*Thanks to Liba Zilber for correcting my typing error.

1 comment:

  1. I found your post very interesting and educational~ thank you for writing this, I will read this through a few more times. I had a number of ah ha moments of clarity :)