DNA and genealogy

That there are many subtleties in the application of DNA data to genealogy can be appreciated from a simple observation. A child generally acquires 50% of its DNA from each parent, thus in effect discarding 50% of each parent's DNA. After a few generations it becomes increasingly likely that all of a parents' DNA will have been discarded in that family line. That is, eventually, even though one knows of a direct ancestor, none of that ancestors' DNA may appear in one's own DNA! This observation does not of course apply in the case of mitochondrial DNA which is transmitted through the female line, and Y-chromosome DNA which is transmitted through the male line.

Notwithstanding such complications this is an active field of enquiry, and interesting findings have been made. In a recent study a promising genetic signature of Sephardic Jews is examined (ref 305). An earlier result is cited - from which it emerges that the Ashkenasim, which comprise the largest Jewish population worldwide, shows a prominent founder effect with only 4 mitochondrial haplotypes comprising 40% of the modern population and with the most frequent haplotype found in 19% of individuals. Sephardim, descendents from Spanish and Portuguese Jews who were the largest Jewish population until the 18th century, instead show a large variation in maternal founders of the communities of the Ottoman Empire. This was especially apparent in their results for Turkey, with the 4 most frequent haplotypes found in only 17% of the present day descendent population and the most frequent haplotype found in not quite 6% (for Bulgaria, the numbers are 27 and 8.5%, respectively). The Ottoman Empire, including Turkey and Bulgaria, received many of the Jewish people who were exiled from Spain and Portugal in the late 15th century. The contrasting findings for the two prominent Jewish populations suggest a greater genetic diversity in mitochondrial DNA in Sephardim than in Ashkenasim. However it is noted that the seemingly higher genetic variability in the present-day Sephardic population does not preclude uncovering Sephardic signatures, the object of the study.

Our distant cousin Michael Waas has conducted a study of male-line Sephardic descent in which some of us participated (see ref 306). His collaborator is Adam Brown who in the online discussion group Sephardic Diaspora during 2019 referred to the Ashkenasi founder effect (see above) and the likelihood that Randy Schoenberg (and hence all of us who descend via the Barrows from Simon Michael Pressburg) does not descend from the small number of original founders of the Ashkenasi community. This discussion is ongoing - but perhaps the ancestors of Simon Michael Pressburg included people from the Sephardic Diaspora. In any event, Michael Waas reported on 25 Jan 2020 that in respect of Julian Land 'we do have some very small 3 centiMorgan segments shared between us. But who knows if that's from the Portuguese or Ashkenasi sides of our families'. Adam Brown's early 2020 update of the use of Y chromosome data in Jewish genealogy is uploaded here. We are exploring with Adam Brown a mini-YDNA project using advanced analysis technology and a small number of male-line Lousadas.

John Griffiths, descendant of Joseph Barrow, has matched his and Julian Land's DNA data on GEDmatch and noted that we have a 3.4 centiMorgan segment match on our 8th chromosome which would put a common ancestor in the early 1700s. This of course matches our known common ancestors Simon Barrow 1709-1802 and Bailah Montefiore 1720-73, but could be due to some other connection. Then, Randy Schoenberg having provided access to his DNA records, John Griffiths and Julian Land found matches with Randy Schoenberg, with one segment match on the 21st chromosome being common to all 3 people, essentially confirming a common ancestor. But the failure of this 21st chromosome segment to show up in the comparison between John Griffiths and Julian Land presumably reflects a match of their 21st chromosome fragments to different half-identical regions of Randy's 21st chromosome (see ref 313 pp154-5). The 3-way comparison is consistent with Julian Land's link with Randy Schoenberg but does not add weight to what we already knew of their de Symons connection; and shows John Griffiths has an independent link with Randy Schoenberg. This independent link would be with Randy Schoenberg's mother, on the assumption that Julian Land's link is the expected one via Randy Schoenberg's father. John Griffiths may have an ancestral link via the Barrows to Randy Schoenberg, but this DNA match does not confirm or deny it, and similarly the additional strength of Julian Land's link to Randy Schoenberg does not confirm or deny the direct Barrow link to Vienna and Bratislava. Nothing needs to be explained in connection with the failure of Randy Schoenberg's DNA to show the 8th chromosome match - this part of his DNA has been effectively discarded.

To this may be added what we have learnt from DNA analysis of de Dirsztay descendants. An anonymous correspondent with probable de Dirsztay ancestry found on FamilyTreeDNA that 'hooray we have the same 5th cousin. I found him in your kit and then went on my cousin's kit .. we both have him....If we both have the same 5th cousin we must be related!' However this match with our anonymous correspondent could have arisen other than via the Barrows. In the absence of further DNA comparisons from our anonymous correspondent, we have been fortunate in that Scott McDougall's wife, a descendant of Bela de Dirsztay 1861-1921, has had her DNA results uploaded to GEDmatch, and a match with Julian Land and John Griffiths confirmed, but not the 8th or 21st chromosome matches above. Again, these matches are suggestive rather than conclusive, but at least do not deter us from maintaining our suggestion that the Barrows via Baruch of Pressburg and Italy have an additional connection with Randy Schoenberg than merely the Lyon de Symons connection and we thus continue to regard Simon Michael Pressburg as a common ancestor.

 DNA analysis may help in a different area. Bob Leuzarder, a probable descendant of the original USA Lousada (Jacob the NY chocolate merchant) made contact, and introduced some immediate relatives and a DNA match also from the USA - Jeannine Wegmueller, a descendant of the Luzarders. While it is not clear how the Leuzarders (see here) and the Luzarders (see ref 314) relate to each other, there are appearing from our work a number of interesting DNA matches with them. John Griffiths has identified over 200 DNA segments shared in each case by a subset of a study group of 11 likely family members, and some details of the D0118, D0216, D0611, D0601 and D2202 matches (using John's nomenclature) may be found here. These 5 segments are shared by 8, 5, 5, 4 and 6 members respectively. However, at this stage all that can be established with complete certainty is that there are non-Lousada matches present in all 5 cases! It should also be noted that John's timescale is affected by the non-Lousada connections for they tend make the matches seem bigger than if they were pure Lousada matches and hence more recent. John's latest report #4 is here, and his observations on this are here. From his work the non-Lousada connections are clearly evident, but it would stretch the imagination to maintain that all those Barrow and Lousada trans-Atlantic connections were due only to the non-Lousada connections. Accordingly, we shall go on to hypothesize a descent of both the Luzarders and Leuzarders from Jacob the NY chocolate merchant, and maintain our pre-existing hypotheses as to the Portuguese origin of Jacob, and the Italian Lousada connection of both the Barrows and the Dirsztays.