About Koestler there was no DNA testing when he lived.I can point you to hundred page studies if you choose ask me but here it sums it very well in wiki
http://en.wikipedia.org/wiki/Jews See also: Y-chromosomal Aaron, Genealogical DNA test, and Matrilineality
Genetic studies indicate various lineages found in modern Jewish populations, however, most of these populations share a lineage in common, traceable to an ancient population that underwent geographic branching and subsequent independent evolutions.[39] While DNA tests have demonstrated inter-marriage in all of the various Jewish ethnic divisions over the last 3,000 years, it was substantially less than in other populations.[40] The findings lend support to traditional Jewish accounts accrediting their founding to exiled Israelite populations, and counters theories that many or most of the world's Jewish populations were founded entirely by local populations that adopted the Jewish faith, devoid of any actual Israelite genetic input.[40][41]
DNA analysis further determined that modern Jews of the priesthood tribe—"Kohanim"—share an ancestor dating back about 3,000 years.[42] This result is consistent for all Jewish populations around the world.[42] The researchers estimated that the most recent common ancestor of modern Kohanim lived between 1000 BCE (roughly the time of the Biblical Exodus) and 586 BCE, when the Babylonians destroyed the First Temple.[43] They found similar results analyzing DNA from Ashkenazi and Sephardi Jews.[43] The scientists estimated the date of the original priest based on genetic mutations, which indicated that the priest lived roughly 106 generations ago, between 2,650 and 3,180 years ago depending whether one counts a generation as 25 or 30 years.[43]
Although individual and groups of converts to Judaism have historically been absorbed into contemporary Jewish populations — in the Khazars' case, absorbed into the Ashkenazim — it is unlikely that they formed a large percentage of the ancestors of modern Jewish groups, and much less that they represented their genesis as Jewish communities.[44]
Male lineages: Y chromosomal DNA
A study published by the National Academy of Sciences found that "the paternal gene pools of Jewish communities from Europe, North Africa, and the Middle East descended from a common Middle Eastern ancestral population", and suggested that "most Jewish communities have remained relatively isolated from neighboring non-Jewish communities during and after the Diaspora".[39] Researchers expressed surprise at the remarkable genetic uniformity they found among modern Jews, no matter where the diaspora has become dispersed around the world.[39]
Other Y-chromosome findings show that the world's Jewish communities are closely related to Kurds, Syrians and Palestinians.[45][42] Skorecki and colleague wrote that "the extremely close affinity of Jewish and non-Jewish Middle Eastern populations observed ... supports the hypothesis of a common Middle Eastern origin".[42] According to another study of the same year, more than 70% of Jewish men and half of the Arab men (inhabitants of Israel and the territories only) whose DNA was studied inherited their Y-chromosomes from the same paternal ancestors who lived in the region within the last few thousand years. The results are consistent with the Biblical account of Jews and Arabs having a common ancestor. About two-thirds of Israeli Arabs and Arabs in the territories and a similar proportion of Israeli Jews are the descendants of at least three common ancestors who lived in the Middle East in the Neolithic period. However, the Palestinian Arab clade includes two Arab modal haplotypes which are found at only very low frequency among Jews, reflecting divergence and/or large scale admixture from non-local populations to the Palestinians.[46]
Points in which Jewish groups differ is largely in the source and proportion of genetic contribution from host populations.[47][48] The proportion of male indigenous European genetic admixture in Ashkenazi Jews amounts to around 0.5% per generation over an estimated 80 generations, and a total admixture estimate "very similar to Motulsky's average estimate of 12.5%."[39] More recent study estimates an even lower European male contribution, and that only 5%–8% of the Ashkenazi gene pool is of European origin.[39]
Female lineages: Mitochondrial DNA
Before 2006, geneticists largely attributed the genesis of most of the world's Jewish populations to founding acts by males who migrated from the Middle East and "by the women from each local population whom they took as wives and converted to Judaism." However, more recent findings of studies of maternally inherited mitochondrial DNA, at least in Ashkenazi Jews, has led to a review of this archetype.[49] This research has suggested that, in addition to Israelite male and local female founders, significant female founder ancestry might also derive from the Middle East.[49] In addition, Behar (2006) suggested that the rest of Ashkenazi mtDNA is originated from about 150 women, most of those were probably of Middle Eastern origin.[50]
Research in 2008 found significant founder effects in many non-Asheknazi Jewish populations. In Belmonte, Azerbaijani, Georgian, Bene Israel and Libyan Jewish communities "a single mother was sufficient to explain at least 40% of their present-day mtDNA variation". In addition, "the Cochin and Tunisian Jewish communities show an attenuated pattern with two founding mothers explaining >30% of the variation." In contrast, Bulgarian, Turkish, Moroccan and Ethiopian Jews were heterogeneous with no evidence "for a narrow founder effect or depletion of mtDNA variation attributable to drift". The authors noted that "the first three of these communities were established following the Spanish expulsion and/or received large influxes of individuals from the Iberian Peninsula and high variation presently observed, probably reflects high overall mtDNA diversity among Jews of Spanish descent. Likewise, the mtDNA pool of Ethiopian Jews reflects the rich maternal lineage variety of East Africa." Jewish communities from Iraq, Iran, and Yemen showed a "third and intermediate pattern... consistent with a founding event, but not a narrow one".[51]
In this and other studies Yemenite Jews differ from other Mizrahim, as well as from Ashkenazim, in the proportion of sub-Saharan African gene types which have entered their gene pools.[47] African-specific Hg L(xM,N) lineages were found only in Yemenite and Ethiopian Jewish populati
Topic: Who is a Jew? - Some insight from Rebbetzen Chana Bracha Siegelbaum (Read 22672 times)