historic mating patterns of ashkenazi jews

i’ve hinted around a few times now that i think — going by some things that i’ve read — that the historic mating patterns of ashkenazi jews (i.e. whether or not they married close cousins and/or practiced uncle-niece marriage) were quite different between western vs. eastern ashkenazis. quoting myself:

“wrt ashkenazi jews: i *strongly* suspect (but Further Research is RequiredTM) that there are two mating pattern histories here — western vs. eastern ashkenazi jews. western ashkenazi jews have, i think, avoided close cousin marriage since the medieval period almost to the same degree as the rest of western europeans. eastern ashkenazi jews — the ones in poland/russia — did not. again, i’m not at all sure about this — this is just what i’ve gleaned from my readings so far. (i will be posting on this one of these days.)

“where western ashkenazi jews differ from the rest of the western european populace is that they were not squeezed through the manorialism meat grinder. in that regard, they must’ve experienced some different selection pressures during the medieval period.”

i first came across this idea — quite a while ago now — in my favorite book, Why Europe?, by medieval and family historian michael mitterauer. he says on pg. 72:

“We find it difficult to comprehend today just how preoccupied the era [the middle ages] was with the fear of incest — and not only in the various Christian churches but in Jewish circles as well.”

he references himself on that — “Christentum und Endogamie” in Historisch-anthropologische Familienforschung — but i haven’t read it yet. one of these days, i just might order it from amazon…and dig out my german-english dictionary.

mitterauer is supported in this by one kenneth r. stow in “The Jewish Family in the Rhineland in the High Middle Ages: Form and Function” [pgs. 1095-96]:

“Unlike Christians, Jews were free to marry cousins and nieces; in the Islamic East, first-cousin marriage among Jews was the norm.[38] In the Rhineland, however, such marriages were somewhat of an exception. This difference may be deduced from the universally accepted Communal Ordinance (*Taqqanah*) proposed by Jacob Tam, the most imposing Jewish authority of his day (d. 1171), on the return of the dowry should the bride die without issue during the first year of marriage. Fathers, the ordinance propounds, should not lose both their daughters and their wealth in one blow.[39] If most marriages had been between first cousins, the respective in-laws, who would also have been siblings, would normally have found ways of resolving issues of money among themselves without the need for legal sanctions. The Responsa (*consilia*) literature, too, legal questions and answers pertaining to actual litigations, supports this conclusion. Responsa may represent exceptions, but they are useful in terms of their specifics or when their decisions reflect precendent or common practices. Thus, in one case, an executor, who was (it should be stressed for its own importance) not a relative of the deceased, married his ward to *his* brother.[40] The brothers of the bride protested, not because she had been married to a non-relative but because they were concerned with the suitability of the match. Had marriage between cousins been the rule, it is doubtful that an executor, especially one who was not a relative, would have dared to violate it.[41]”

so, stow doesn’t have hard-and-fast data on marriage types here — he’s making a deduction — but i think it’s a good one. what i find particularly persuasive is the fact that the family type of these medieval rhineland jews was primarily nuclear (or stem). in other words, according to stow, just like the broader western european population, medieval rhineland jews did *not* have clans. and that seems to be the general pattern: the more outbreeding, the smaller the family size.

fast forward to the nineteenth century (yes, that is an unacceptably large gap), in alsace-lorraine, the consanguinity rate amongst jews was 2.3% (whether that was first and second cousins or just first cousins, i don’t know) [see this post]. that is a very low rate by any standards. in comparison, though, the consanguinity rates for protestants in the region was 0.2% and for catholics it was roughly 1%, so the jewish cousin marriage rate was higher.*

if we move slightly to the east to what i infer must’ve been (at the time) the province of hohenzollern, we have these figures from steven m. lowenstein [“Decline and Survival of Rural Jewish Communities” in In Search of Jewish Community: Jewish Identities in Germany and Austria 1918-1933, footnote 44 on pg. 241]:

“In Hohenzollern, there was an 11 percent rate of marriage to relatives (5 percent to first cousins) among Jewish couples who died before 1922; of those still alive in 1922, the rate had increased to 22 percent (16 percent to first cousins). These rates were several times as high as the rates for Christian marriages. See Wilhelm Reutlinger, ‘Uber die Haufligkeit der Verwandtenehen bei Juden in Hohenzollern und uber Untersuchungen bei Deszendenten aus judischen Verwandtenehene,’ Archiv fur Rassen- un Gesellschaftsbiologie 14 (1922): 301-303, quoted by Marion Kaplan The Making of the Jewish Middle Class: Women, Family, and Identity in Imperial Germany (New York, 1991), p. 273 note 206.”

so, higher cousin marriage rates in this region amongst the cohort closest to the alsace-lorraine group above — 5-11% versus 2.3% (remembering that that latter figure might be just first cousins). and much higher rates post-1922, the author argues because jews were leaving the german countryside during this time period, so potential marriage partners were becoming scarce. still, while a 16% first cousin marriage rate is high for northern europe, it’s not even close to the 30%+ first cousin marriage rates in sicily in the 1960s! and the earlier 5-11% rate may have been more “normal” — hard to tell — Further Research is RequiredTM.

if you thought all that was vague, the info for jews in eastern europe is even less clear. (>.<) it's basically just anecdotal evidence — a lot of people saying that cousin marriage was very common in eastern european ashkenazi communities. i wrote a whole post about it: jewish mating patterns in nineteenth century russia. this quote is from Jewish Marriage and Divorce in Imperial Russia [pgs. 25-27]:

Although data on consanguineous marriages in Russia are lacking, contemporaries claimed that they were ‘very common,’ largely because of the narrow circle of eligible partners for any given class of Jews. This geographic endogamy impelled one Jewish observer to write that ‘the expression “Kol Yisrael ahim” or “all Jews are brothers” is true in this sense, that Jews [who] belong to one strata of society and reside in one area, always find out that they are related when discussing their family backgrounds.’ The strategy of marrying relatives was particularly pronounced in small towns. It was due to concerns about family lineage, as well as to restrictions on geographic mobility (i.e., legal restrictions on residency, poor communications and transportation, and the high costs for travel).

“That observation indeed finds confirmation in the metrical records. These archival materials are unusually complete for Korostyshev, a small town in Kiev province with 2,657 Jewish residents in 1847. Unlike many Ukrainian towns where the metrical records were destroyed during World War II, Korostyshev preserved metrical books from the mid-nineteenth century to 1915, thus representing some of the most complete runs of Jewish metrical books in the entire Ukraine. Significantly, they reveal that most residents married locally — that is, to people from Korostyshev or, at most, from nearby villages and towns (Zhitomir, Berdichev, and Radomysl’). Still more striking were the marital bonds between small family networks — for example, the countless marriages among the Fuksmans, Gershengorens, Trakhtenbergs, and Ratners (all of whom lived in Korostyshev or nearby Zhitomir). Another network included the Vinikurs, Tsiponiuks, and Abrumovichs; this cluster overlapped with a group that included the Kagans, Umerskiis, and Peigers. And so on until, several decades later, many Korostyshev residents were distant or even close relatives. Devorah Baron’s description of small shtetl families was indeed perspicacious: ‘In our little town, families joined together by marriage ties often resembled well-fitted but separate sections of garment; all that was needed was the skillful hand that would join the seams.’”

in the late nineteenth century, russian-jewish leaders tried to do something about all this cousin marriage (these reformers were inspired by all the talk about the dangers of inbreeding generated by the darwins and galton, just as the japanese were) [pgs. 27-29]:

“In the late nineteenth century, Jewish reformers castigated this consanguinity as detrimental to family health. The developments in contemporary medicine (especially eugenics and clinical psychiatry) had a profound impace on public discourse; as physicians joined in, the debate on Jewish marriage became increasingly medicalized. ‘Owing to heredity,’ warned the ‘Evreiskii meditsinskii golos’ (The Jewish medical voice), ‘all physical defects appear in the offspring with particular force, since the definciencies of both parents are aggregated. Invoking Western science, Jewish physicians ascribed the increased rate of ‘nervous disorders,’ such as hysteria, epileptic seizures, imbecility, and insanity, among the Jewish in Russia to their pernicious inbreeding.

“Samuel Gruzenberg (1854-1909), who held a degree from the Medical-Surgical Academy in St. Petersburg, publicized a series of essays in an influential Jewish journal. Representing the views of the medical establishment, he warned parents that ‘nervous illness’ and hereditary diseases, such as blindness, deafness, and muteness, posed a threat not only to the immediate offspring but also to subsequent generations. Endogamous unions, he declared, also produced a large population with unhealthy ‘national physical features’ — namely, ‘a short [body], weak muscles, and especially … a high level of nervousness.’ Citing a study on army conscripts, he noted that nearly half of the Jewish recruits failed to meet the physical requirements and exhibited ‘extreme forms of the Jewish physical type.’

“It was no accident that Gruzenberg cited the Jewish recruit to demonstrate the evil of consanguineous marriages: the physiognomy of male offspring greatly concerned reformers. In contrast to the modern ideal of man, who displayed ‘virility, proportion, and self control,’ the asthenic Jewish conscript embodied all the traits of the effeminate Jew so despised in European society. Whereas Jewish society had long associated a pale, slender Jewish body with Torah scholarship and edelkayt (nobility), reformers now scorned this model as passive, cowardly, and feminine, a clear indication that the reforemers had embraced the new European construction of masculinity. The inbreeding affected not only the body but the mind: ‘Moral sickness and physical sickness were thought to be identical — the latter leaving an imprint on the body and face….’


“[T]his public debate did not reduce the frequency of consanguineous marriages….”

so, from all of this medical hysteria, i am guessing that the historic cousin marriage rates among jews in eastern europe were much higher than those in the west — at least in the nineteenth century.

sephardic jews have historically had much higher rates of consanguineous marriages than ashkenazi jews — up to 20% in some places according to joseph spitzer [pg. 160]. see also this post: jewish endogamy on mallorca. same with mizrahi jews — for example, the rate of consanguineous marriages among iranian jews in 1991 (first and second cousin plus uncle-niece marriages) was 25.4%.

it seems to me that jews — wherever they have lived (outside of judea/israel, i mean) — have generally copied the broader population’s mating patterns. in medieval western europe, they avoided close cousin marriage and, according to mitterauer, were very worried about incest in the same way that the rest of western europe was at the time. in eastern europe, though, they appear to have married their cousins with greater frequency, probably down through the centuries not unlike the rest of eastern europeans. in the nineteenth century, however, some eastern european jews began to be influenced by ideas on outbreeding coming from western europe. sephardic jews had high cousin marriage rates, just like southern europeans. and jews in north africa and the middle east have extremely high cousin marriage rates — same as the rest of the populations in those places. (for more on the histories of mating patterns in each of these regions, please see links to posts below ↓ in left-hand column under the “mating patterns in” series.)

long-term outbreeding (since the middle ages) of western ashkenazi jews would fit with the genetic evidence which indicates that ashkenazi jews are not inbred (see razib’s posts here and here). all the apparent historic cousin marriage of eastern ashkenazi jews would not fit with that. i’d like to see the genetic data (runs of homozygosity) for ashkenazis parsed out between eastern and western europe to see if any differences can be detected. my guess is that they should be there (there should be more roh in russian jews than in german jews), but i could be wrong.

so, the reasons i think that western european jews must’ve avoided close cousin marriage over the long-term, whereas in contrast eastern european jews did not, are:

– the scanty historic data (i will dig around for more of that);
– the somewhat supportive genetic data;
– the circumstantial evidence suggesting that jews have tended to copy the mating practices of their host populations;
– and that, by the high middle ages, western european jews did not have clans but, rather, had nuclear (or stem) families.

as i mentioned in my self-quote at the start of this post, though, european jews did not experience whatever selection pressures were connected to the bipartite manorialism of medieval europe. one of the things that i think was selected for via the manor system was the late marriage practices (i.e. delayed gratification) of northwest “core” europeans. western ashkenazi jews, on the other hand, continued to marry very young right into the early modern period, perhaps because they were never manorialized.

(yes, this is me gearing up to respond to professor kevin macdonald’s recent post On the HBD Chick Interview. i’ve got a couple of other “prep” posts i’d like to do first, though, before i get to my response. stay tuned! (^_^) )

previously: inbreeding in nineteenth century alsace-lorraine (including jews) and jewish mating patterns in nineteenth century russia

*i also have some data for jewish cousin marriage rates in nineteenth century england, but shortly after writing that post, i decided that those data need to be disregarded. see this post for my reasons why.

(note: comments do not require an email. medieval german jews. and a duck!)


  1. @ihtg – “That Hoover Hog interview is from 2013. Took him a while.”

    well…at the rate i’m going, i feel like it’s going to take me all the way until next year to get my thoughts organized and response prepared. (*^_^*)


  2. Interesting. If it is true that cousin marriages were much rarer in Western than Eastern Europe, would this result in differences in their respective mentalities (degree of ethnocentrism in particular) according to your hypothesis about inbreeding. In particular, we sometimes read of distinguished Jewish families in Eastern Europe with rabbis running back seven generations or more. Given that rabbis were a tiny percentage of the population (<1%) would this imply higher rate of inbreeding among the intellectual elite? Might this account for some of the more visceral examples anti-whitism we see displayed among certain prominent Ashkenazi journalists and pundits?


  3. So the monarchical elite-aristocracy, and certain guild ethno groups ( Jews, gypsies ) practiced familial marriage, while the elite’s church discouraged such tribalism in the gentry and working classes, thus atomizing human extended family groupings into the new men of progress.

    which explains why Europeans have yet to conquer and hold China and the MENA regions.

    first blow up basic mammalian social groupings, THEN occupy, enslave, trade

    social parasitism


  4. I don’t see how cousin marriages could not have been as high or even higher among western European Jews – higher than among the mass of Ostjuden – simply because there were so few of us, spread so thinly. In the heartland of Jewish Germany, the upper Rhine,there were 22,000 Jews among 1.6 million Rheinlanders in 1800, spread among hundreds of small towns. In Poland-Lithuania before the partitions of 1765, there were 750,000 Jews out of a total population of 11 million – in a much bigger area, but for the most part highly concentrated. The Jewish population of the entire Napoleonic empire was only 65,000 at that time, including the 22.000 German Rhineland Jews. I believe that the proportion was the same in Bavaria. And 20,000 is not just a small proportion of 1.6 million, but a small absolute number, for people forbidden from marrying outsiders. In the east, on the other hand, there were bigger cities with concentrations of Jewish population as well as a total population that was many times bigger. And with men having children with 2 wives from different families in the same community, the math of finding a spouse who was not at least a second cousin was even worse.
    When the two groups first came to America, separated by 40 or 50 years, each behaved as their ancestors did. The Germans scattered themselves among hundreds of American small towns and small cities from Oregon to Georgia, and the eastern Ashkenazi clustered in the biggest cities, where anything could happen – even a Litvak marrying a Rumanian.
    I know that in the half of my family from Germany, even though they immigrated in the 1840s, a cousin of my grandmother’s – unaccented, a member of the Masons and the Elks, leading merchant of a major Southern city – arranged in 1905 for his youngest brother to marry his niece (daughter of his wife’s sister) without causing any shock at all. It wasn’t incest, it was business.
    I also think you must draw a line between what happened in Germany pre-railroad and post-railroad, between life at the beginning of the nineteenth century and the middle. Germany changed almost as rapidly as America at the same time. The world of Russian Jewry that the blessed RaeLee Y. Chan describes in her great book didn’t exist 50 – 100 years before her starting date of 1820, because it wasn’t in Orthodox Russia, but in Catholic Poland-Lithuania! The urban Jewish world that we think of in Berlin, Prague, and Vienna didn’t yet exist in 1800. What did exist was a Jewish world in the east, with towns that were 20%, 33%, 50% Jewish, and a Christian/bureaucratic/aristocratic world in which a few Jews could scratch out a living in the west, in towns that contained a handful of Jewish families.


  5. @penitenziagite – “So the monarchical elite-aristocracy, and certain guild ethno groups ( Jews, gypsies ) practiced familial marriage….”

    you rather missed one of the main points of the post there, i.e. western ashkenazi jews appear to have been outbreeding nearly as much as other western europeans for about the same length of time (since the medieval period). Further Research is RequiredTM.


  6. @sam – “I don’t see how cousin marriages could not have been as high or even higher among western European Jews – higher than among the mass of Ostjuden – simply because there were so few of us, spread so thinly.”

    and yet the actual numbers for western european jews are very low — 2.3%-11% (a max 16-22% in unusual circumstances) — while the anecdotal reports out of eastern europe are that ashkenazi jews there were marrying cousins left and right. some real data for the pops in the east would be nice, of course.

    also, remember we’re talking about evolution here — that’s why i’m interested in casting the net back to the middle ages. again, very interesting that western european jews were reportedly concerned about avoiding incest in the 1100s (and the circumstantial evidence suggests that they probably did), while the same was barely even happening at the time among russians and other eastern europeans, let alone any jews in eastern europe at the time.

    like i said, i think the evidence so far strongly suggests that this east-west mating patterns divide existed between eastern and western ashkenazi jews. Further Research is RequiredTM, tho.


  7. Here’s a theory for you:

    Feminists are a phenotypic morph.
    Feminism is political-ideological weaponization by that phenotypic morph.


    Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species—in other words, the occurrence of more than one form or morph. In order to be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating).


    “Stay or stray? Evidence for alternative mating strategy phenotypes in both men and women”

    This study shows there are two disitnct phenotypes within human populations. Promiscuous people and non-promiscuous people. Promiscuous = low digit ratio=higher testosterone=short-term mating strategy.


    “Feminist activist women are masculinized in terms of digit-ratio and social dominance: a possible explanation for the feminist paradox.”

    This study shows that feminists are masculinised in terms of digit ratios=lo digit ratios=higher testosterone.

    This explains why feminism is about changing society from long-term to short term mating. It explains why they defend women being sluts. It explains why they defend women cuckolding. It explains why they defend and agitate for women to pursue careers and achieve self-provisioning sufficiency. And it explains why they try to change the culture to support these values and necessarily oppose their anti/inverse values.

    Thus, there is no right-wing war on women. There is a right wing war on the short-term mating or feminist or matriarchal morph.

    Likewise there is a left-wing war on the long-term mating or anti-feminist or patriarchal morph.

    And here’s the catch; most women are in the long-term mating / anti-feminist / patriarchal morph.

    In other words. feminism is anti-(the majority of)-women.


  8. Jews and specially, ashkenazic ones, have very higher rates of autoimmune problems because, fundamentally by its bio-etiology , heredity of higher rates of anomalous laterality. With the exception of alcoholism, ashkenazis have most of all implications of different or unusual brain organization. It explain can explain heterozygosis. If endogamy really cause physical weakness, how explain amish muscles or even, muslims??? More jews are gay, narcisistic, macchiavelian, atheist, artistic…

    unusual brain organization. Endogamy


  9. @lukelea – Jewish Marriage and Divorce in Imperial Russia
    By ChaeRan Y. Freeze. HBDChick also uses and cites it. There’s a good little book by Jonathan I. Israel, European Jewry in the Age of Mercantilism, 1550-1750 (1998), which gives a great account of the movement of Jewish population to the underpopulated far frontiers of European power in the 16th and 17th century – to the eastern/southern Ukraine and the Polish borderlands in the east, and to the banks of the Suriname River in northern South America (the Jewish Savannah) in the west. At precisely the same time, German Gentile peasants moved from precisely the same parts of Germany to settle Transylvania (between Hungary and Romania), the Ukraine and farther into Russia itself (where Jews weren’t welcome.) [here’s a beautiful map that HBDChick I think tweeted today: https://twitter.com/BeautifulMaps/status/570646249038336001/photo/1) The Western settlements didn’t work out so well, but in the East, Jewish population growth was astounding. So I think it possible that eastern and western practices diverged sharply in a relatively short time between the 17th and 19th centuries, simply because the economic + social lives of Jews who remained in the Rhineland remained as it was in 1100, while the frontiersfolk were rocketed into modernity.
    HBDChick, you do the work. I’ll keep thinking!


  10. oh and I meant to say – that in these regions, when the Jews first entered, there simply wasn’t a lot of social/marital context to adapt to, or whose customs might be adopted, because they were underpopulated or nearly drained of population. (The central + southern Ukraine and Odessa were underpopulated because of Ottoman and Caucasian/Mongol slaving that removed hundreds and hundreds of thousands of people from the stepped in the centuries before the 17th century. So it wasn’t like the German Rheinlands, where, when Jews had to adopt new non-Jewish-sounding names by Napoleonic decree in 1808, all the Frumas and Shoenes became Charlottes and Elisabettas overnight. There was no social standard. It was more like Little House on the Prairie than Jane Austen.


  11. @sam – So I think it possible that eastern and western practices diverged sharply in a relatively short time between the 17th and 19th centuries, simply because the economic + social lives of Jews who remained in the Rhineland remained as it was in 1100, while the frontiersfolk were rocketed into modernity.”

    well that could very well be, but i honestly don’t think that the jewish folks who moved eastwards began to marry their cousins (or nieces) less. i really do think it went in the other direction.

    BUT!…need to find out for sure. mostly just supposition on my part so far. (^_^)

    thanks for the reference to israel’s book!


  12. I don’t get it — don’t the papers that Razib links to lay out very good genetic evidence that Ashkenazi Jews AREN’T particularly inbred? His summary:

    “So, when considering “inbred” as in the products of frequency cousin marriages, Ashkenazi Jews are not inbred in that manner. They don’t exhibit an abnormal level of very long IBD tracts, which is what you get floating around in the population with there are lots of extremely recent common ancestors between one’s two parents.”

    The sample from the study Razib references comes from the metro NY area. Most Ashkenazi Jews in NY are descended from eastern, not western, immigrants; you using that as genetic evidence of western Ashkenazi outbreeding is a mistake. To me the genetic studies showing Ashkenazis as NOT being inbred is a lot stronger than hearsay and pre-modern medical essays — wouldn’t you agree?

    Your general hypothesis is that inbreeding causes clannishness, and outbreeding causes individualism. In this post you also argue that western Ashkenazi aren’t inbred while eastern ones are; thus, the former should be less clannish and more individualistic than the latter. However the historical evidence doesn’t show this as all. For example, 19th-century German Jewish immigrants in the US would probably classify as extremely clannish. You can read about this community in “Our Crowd” by Stephen Birmingham and you’ll see how tightly interwoven social life, business, and romance were for the German Jews. Regarding marriage practices — no cousin marriage I can remember, but most definitely networks of families continuously marrying each other. I don’t know for sure but this seems to me something common amongst many upper class people across space and time.

    On the flip side, I see very little evidence of heightened eastern Ashkenazi clannishness. I’m acquainted with many Russian-Jews who immigrated to the US in the 80s and 90s when the Soviet Union collapsed; all I witness is quick assimilation into mainstream American culture and definitely a focus on individualism over family ties. Plus, the intermarriage statistics speak for themselves. So, again, where is the evidence?

    All this points to the fact that “culture” and other external factors do indeed matter. And yes, I agree that culture is shaped by genes, yet it seems that the range of cultures/behaviors that can arise from identical genetics is *quite* wide…

    PS. Apologies for sounding like I’m just trying to poke holes in your argument — I do love that you’re asking these questions and coming up with interesting answers, even if I don’t agree with some of them. Though I think as a bona fide truth-seeker you would appreciate having your feet held to the fire. :)


  13. @sprfls – “I don’t get it — don’t the papers that Razib links to lay out very good genetic evidence that Ashkenazi Jews AREN’T particularly inbred?”

    they lay out *pretty good* genetic evidence that ashkenazi jews aren’t particularly inbred, but 1) runs of homozygosity (roh) would be even better than the identity by descent (ibd) distributions that the papers offer. the latter are indicative, but the roh would nail the inbreeding better (although still with some problems); and 2) everything’s relative…

    from the paper which sampled ashkenazi jews in nyc:

    “…the Ashkenazi Jews exhibited increased sharing of segments at the shorter end of the range (i.e., 5 cM length), but decreased sharing at the longer end (i.e., 10 cM) (Figure S5)”

    sure, 5 cM is low compared to what you’d find in highly inbred arab populations, but it’s higher than the rates western europeans exhibit. it’s even higher than the average found in russians (4.3 cM) and much higher than that found in germans (1.1), the french (0.7), or the english (1.2) [see this map from this post].

    if those *are* the average ibd lengths of russian/eastern european ashkenazis as you suggest (and, yeah, nyc…that could make sense), then that would support my argument that eastern ashkenazis are more inbred than western europeans. however, these ibd rates are a little tricky to interpret, because of founder effects, etc. — do they really represent inbreeding rates or also that the group went through a bottleneck or two? that’s why roh would be better.

    AND we’re still left not knowing what the western ashkenazi rates look like, if these were indeed mostly russian jews as you suggest. that’s why i’d like to see the genetic evidence parsed out for the two subgroups.

    @sprfls – “you using that as genetic evidence of western Ashkenazi outbreeding is a mistake. “

    no, i didn’t used the genetic data as evidence of western ashkenazi outbreeding. i said the two would (i.e. could) fit together, not that i know for sure that they do.

    @sprfls – “On the flip side, I see very little evidence of heightened eastern Ashkenazi clannishness.”

    i think i do see hints of that. another big divide between western and eastern ashkenazis that i see is that more “open” (more modern, liberal) forms of judaism developed in the west — like reform judaism — while more “closed” (traditionalist, clannish) forms appeared in the east — hasidic judaism, for example. we even know that hasidic jews practice uncle-niece marriage rather frequently. which came first, then, the traditionalist religious beliefs or the inbreeding? my money is on the inbreeding.

    @sprfls – “Apologies for sounding like I’m just trying to poke holes in your argument….”

    no, no! don’t apologize! poking holes is good. (^_^) skepticism is good! (^_^) and Further Research is RequiredTM. these questions are not answered yet!

    i’m sorry that i didn’t reply to your comment sooner, though. i was busy soaking my feet in a bucket of ice water. (~_^)


  14. @sprfls:

    “All this points to the fact that “culture” and other external factors do indeed matter. And yes, I agree that culture is shaped by genes, yet it seems that the range of cultures/behaviors that can arise from identical genetics is *quite* wide… “

    Identical genetics? You sure about that?

    “The sample from the study Razib references comes from the metro NY area. Most Ashkenazi Jews in NY are descended from eastern, not western, immigrants; you using that as genetic evidence of western Ashkenazi outbreeding is a mistake.”

    You sure about that? Do the Jews in the Upper East & Upper West Sides in Manhanttan originate from the same areas as the Jews in say Brooklyn (the latter of which is definitely heavily Russian)?

    As well, as Chick says, I’m not sure IBD is a good measure levels of inbreeding that’s relevant here. IBD tells you how related one individual is to a random other individual in their population. A long history of inbreeding makes individuals more related to their close relatives with respect to everyone else, not to the population in general. Indeed, that degree of relationship is largely unaffected (being mostly a product of bottlenecks and reproductive isolation than anything else). The number of and length of runs of homozygosity serve as better measures. I don’t know how well that has been measured in Jewish populations.

    “Plus, the intermarriage statistics speak for themselves.”

    Not really.

    I think Chick covered the liberal/conservative (i.e., unclannish/clannish) divide between western and eastern Ashkenazis.


  15. I wouldn’t look at different religious practices between east and west, but different economic practices – and then look differently at eastern religious practices. Eastern Jews were in the old world and the new far more likely to be entrepreneurial, venturesome, and risk-taking. The pre-1880s German Jews in the US continued their old-world businesses on a larger scale – peddlers to department stores, jewelers, distillers, middlemen. But Jews in the Russian empire who succeeded suceeded on a bigger scale – supplying Russia’s tea, sugar, matches,machine tools, chemicals, and revolutions (as the Russian gentry told one another after the February revolution), and in the US their commercial success in the 1920s onwards overwhelmed and surpassed all but a few of the old German-Jewish fortunes. Now back to religion: Reform Judaism was highly Germanized and imitative of German Protestantism. Whereas in the East, Orthodox Judaism faced competition from flamboyant alternatives – Hassidism with the stuff we all know about and the new stuff we’re just learning about – furious and often violent conflict between Hasidic clans; and even more, Frankism and other forms of Sabbataism that survived and thrived in Poland-Lithuania from the late 1600s on, with tens of thousands of adherents and perhaps tens of thousands of conversions to Catholicism. Eastern European Judaism thought big and acted on a big scale. Even the thriving Jewish metropolises that we think of as German – especially Berlin, Prague, Vienna – were populated with hicks who had immigrated from the East, who had overwhelmed the “indigenous” western Ashkenazi to the same degree that the 150,000 or so genteel, “refined,” Masonic and BPOE type of German Jews who arrived in the US pre-1880 were overwhelmed by ten times that number from the Russian and Austrian empires after 1880.


  16. @jayman: biggest difference between Jews of UWS/UES and Russian Jews of Brooklyn would be that the grandparents/parents of Jews who remained in + survived in USSR + then immigrated in 1970s-90s were FAR more likely to intermarry than were the grandparents + parents of the “American” Jews, so they would be – less Jewish. I suppose more likely to have been descendents of better educated Jews in the period 1880-1920, possibly university graduates, who were needed by the Imperial and then the Bolshevik state in a way that the “world of our fathers” immigrants were not. But the banning of Jewish religious and communal life and Party encouragement of intermarriage had a strong effect on the population, though I’ve never seen it quantified. It could easily be 20-30% Gentile among 1980s immigrants.


  17. @HBD Chick

    Thanks for the response. I think we can agree that Ashkenazi in general are more inbred then western Euros, yet *much* closer to them than they are to highly inbred populations.

    The question becomes, then, whether something like a ~2% cousin marriage rate is enough to make a real impact? On one hand, it is an order of magnitude more than ~0.2%; on the other, it’s still very low in an absolute sense. There may be a tipping point required for a noticeable group-wide effect to occur. I’m sure you’ve thought about that before though. :)


    “Identical genetics? You sure about that?”

    I meant that as a general statement. So, yes, I do believe that if we randomly drop one group of identical aliens onto sufficiently different planets, they will exhibit different behaviors based on the unique challenges of each planet, and that the range of possible behaviors that can arise is fairly wide.

    Do I think that western and eastern Ashkenazi are identical genetically? Yes, I do — but I’m not sure. I guess you’re implying that either cultural changes leading to higher frequencies of cousin marriage *changed* easterners over time, or that the population was sorted meaningfully by the eastward migrations themselves. I think both are false, but, as our humble host likes to say, Further Research Required. :)

    Of course, cases of human groups splintering can’t be claimed to be random, but how non-random they are I have no idea. Each case is unique.

    “You sure about that? Do the Jews in the Upper East & Upper West Sides in Manhanttan originate from the same areas as the Jews in say Brooklyn (the latter of which is definitely heavily Russian)?”

    Yes, I’m sure. Roughly 10x more people migrated from eastern rather than western Europe. So, if the authors had a representative sample of Ashkenazi Jews from the NY Metro Area, and didn’t just go knocking in the hallways of the Dakota, then yes — I’m sure.


    Generally those that have the most to lose are the ones least likely to immigrate. This goes back to the point of non-random sorting when a previously identical group splits. I do wonder if this played a role in sorting Jewish emigres from Tzarist Russia, and perhaps helps explain why the more recently arrived Russian Jews are *way* more conservative than “American” Jews. I don’t think so though — a reaction against experiencing life under *actual* communist rule is probably the culprit here. Though it’s all definitely interesting to ponder.


  18. @sprfls – “The question becomes, then, whether something like a ~2% cousin marriage rate is enough to make a real impact?”

    well, the issue is not a 2% cousin marriage rate. that’s the rate for western ashkenazi jews in the nineteenth century in alsace-lorraine (the rate’s a bit higher, remember, in hohenzollern — a 5% first cousin marriage rate). i agree, those rates are undoubtedly not high enough to make any sort of impact (edit: or, rather, if those were the rates for long enough, western ashkenazi jews might’ve evolved to be individualistic and universalistic rather than clannish!).

    what i’m guessing is that the rates in eastern european jewish groups were much higher. plus there was/is the uncle-niece marriage phenomenon — that’s even closer than first cousin marriage, of course. if the rate of cousin marriage among eastern european jews was even half that of sicilians in the recent past, then that could’ve/would’ve made an impact.


  19. Even if Eastern Ashkenazi are inbred to some extent it certainly didn’t effect their iq or success level. What really matters in modern world is the average iq and outbreeding itself does not increase it.


  20. @cpluskx – “What really matters in modern world is the average iq and outbreeding itself does not increase it.”

    iq is undoubtedly very important in the modern world. but it ain’t everything. if it were, the chinese or the japanese would’ve gone to space first. and russia today wouldn’t be such a basket case.


  21. IQ usually works very well for a lot of things: gdp per capita, nobel prizes, general state of a nation even smpy kids, etc. East Asians are not good at the highest levels (nobels etc.) I think probably state selection for authoritarianism, societal selection for more respect to hierarchy less for creativity or something like testosterone levels may have to do with it. Also Europe/Middle East exchanged a lot of information, East Asia was disconnected to some extent. (You can’t get anything done even if you are an Ashkenazi in Poland and not US) All these things effected East Asia’s development. (And Mongol Destruction) Russia is probably a result of state selection too. In MENA iq declined by at least 1 sd after Islam so they are already out.
    I am not sure if it has to do with outbreeding, in Europe higher classes had more reproductive success and lower classes didn’t replace themselves, that’s how Europe started to advance. Those higher classes were individualistic/liberal etc. Also i saw one IBD data and according to it very individualistic Sweden was more inbred than Romania/Hungary/Greece. Are there any research which shows a different result?


  22. @Cpluskx:

    “I am not sure if it has to do with outbreeding, in Europe higher classes had more reproductive success and lower classes didn’t replace themselves,”

    It does Cpluskx. Seriously, ultimately, what else makes the difference between NW Europe, vs NE Europe and East Asia?

    I think I’ve seen enough silly statements in the past few days.


  23. JayMan: Are there any research which shows that NW/NE Europeans are the most outbred populations? I saw your map and it looks like you just painted the most developed (currently) parts of Europe as least inbred.


  24. @cpluskx – “Are there any research which shows that NW/NE Europeans are the most outbred populations?”

    yes, there is. this blog! (^_^)

    see all the links in the “mating patterns in…” series below ↓ in left hand column. you might want to start here, tho.


  25. @cplusk – “I want to see the numbers…”

    well, there aren’t all that many numbers yet as genetic studies are still in their infancy and very few researchers to date have been directly interested in the inbreeding rates. so you really shouldn’t overlook the historical data on mating patterns, because right now they give us the strongest indications of what’s been going on. if you are interested in the topic, i urge you to read the posts i’ve linked to in my ‘start here’ page.

    having said that, there are a handful of genetic studies you can look at. first of all, have a look at the contemporary consanguineous marriages map at consang.net. although those are contemporary figures, they also reflect a fairly good idea of the mating patterns in the old world regions for the last thousand years or so. there are some errors. the numbers for italy are way off. and the averages for japan and china likely only reflect the last hundred years or so.

    here are some genetic studies. keep in mind that runs of homozygosity (roh) are much more indicative of inbreeding (or outbreeding) than ibd (identity by descent) rates, but the ibd rates are not absolutely terrible, either. one would expect to find greater numbers of longer ibd segments in an inbred population, but other things can affect those rates as well (founder effects, etc.). also, some difficulties with the genetic data: 1) we often don’t know the *exact* provenance of genetic samples so, for example, the hbdp samples from france — where in france? there have historically been different inbreeding rates in different regions in france; and 2) the different studies often measure different roh or ibd lengths making it difficult, if not impossible, to compare the different studies:

    runs of homozygosity and inbreeding (and outbreeding)
    runs of homozygosity again
    hgdp samples and relatedness
    more on the hgdp samples
    why i care about the hgdp samples
    the hgdp samples again
    ibd and historic mating patterns in europe
    more on ibd and historic mating patterns in europe
    ibd rates for europe and the hajnal line
    western europeans, runs of homozygosity (roh), and outbreeding
    russians, eastern europeans, runs of homozygosity (roh), and inbreeding
    runs of homozygosity in the irish population


  26. Hbd chick: Thanks for the answer, i’ll look at the links. Consang.net shows lower consanguinity for Eastern Europe. If those contemporary figures reflect a good idea of past mating patterns isn’t that contrdicting your Hajnal Line theory?

    Ok after writing this i looked at this link:


    Russians are less inbred than Finns, usually less inbred (especially in the large population areas of Western Russia) than Baltics and Poland. Also not very different than Czechs. All these populations are quite liberal/individualistic compared to Russia. Lots of contradictions with Jayman’s map.


    South Eastern Europe, places like Greece (including Southern Greece), Romania, Western Ukraine and Northern Portugal are less inbred than Scots, Scandinavians and usually NW Europeans. Southern Italy is less inbred than Scotland too. Finns are once again quite inbred.

    Well i see lots of contradictions with your theory by looking at three different inbreeding indicating maps. (but certainly better data needed, these maps show different results) Correct me if i am wrong at something.


  27. @Cpluskx:

    Critical analysis is of course very good, and extremely important.

    Unfortunately, your understanding of the matter is only superficial, perhaps understandably so. So let’s take a closer look at your objections.

    Before we start, read this post by Razib Khan. While runs of homozygosity (ROH) are the best way of inferring inbreeding, inferring the degree of historic inbreeding from ROH is somewhat complicated. You need to look at multiple lengths. The studies discussed in those older posts looked only at shorter lengths, which doesn’t give you the full picture.

    Sampling is also an issue. Many are urban samples, which, as HBD Chick discussed, aren’t necessarily representative (urban residents tend to be less inbred). Ideally we’d like to see samples from multiple regions across the whole continent, and not limited to the major cities.

    Now, those said, let’s actually take a look at these data. Khrunin et al clearly show enrichment in ROH in Russian and Eastern Europe relative to the Germans and Central Italians, just as HBD Chick’s theory predicts, and just as my map depicts. You see considerably elevated levels of these short ROH in Finland, but see the above point.

    As for Northnagel’s study, we see the problem of relying on short ROH only, but also here – if you look only at the precise locations the data were drawn – the levels essentially agree with the expected ones, with perhaps some small exception in Southeastern Europe – and all of those look like they come from major cities given their locations on the map.

    Like HBD Chick said, unfortunately, we don’t quite have the amount of quality genetic data to test that part of the theory, yet.


  28. @cpluskx – “Russians are less inbred than Finns, usually less inbred (especially in the large population areas of Western Russia) than Baltics and Poland. Also not very different than Czechs.”

    weeeellllll, it’s not that easy to tell, unfortunately, from the genetic data (at least right now) what the “inbrededness” of a populations is, which is why i place so much emphasis on the historic data. like i said in my comment above, “other things can affect those rates as well (founder effects, etc.).”

    so, as far as russians being less inbred than the finns. maybe. but maybe not. they do have lower roh rates according to that one study, but as i said in that previous post:

    “finally, the authors of the study point out how it appears that the average number of roh in individuals in a population increases with latitude — and they mention that this has also been shown elsewhere (i’ll be posting on that paper — very soon!)…. the authors suggest that this is due to the general pattern of how europe was settled (from the south to the north), as well as the fact that the farther north you go, the fewer people there are to mate with (so the more inbred you wind up being).”

    so somehow we’ve got to calibrate the roh rates for peoples at different latitudes in order to be able to “see” the cousin marriage in populations (if there was any). the high roh rates due to low population size (or bottlenecks, etc.) might be obscuring the inbreeding rates due to consanguineous marriages.

    in other words, even roh are not an ideal way to look for histories of inbreeding.

    wrt to the other post, you said: “South Eastern Europe, places like Greece (including Southern Greece), Romania, Western Ukraine and Northern Portugal are less inbred….”

    as i said in that post:

    “the researchers, btw, acknowledge that the areas indicated as having very low amounts of roh — colored in the lightest shades of yellow — i.e. northwest spain and eastern europe — are probably artifacts of the interpolation method that they used.”

    again, this is why i bother hunting around for historic data on mating patterns for populations — the genetic data just really isn’t available (and understandable) yet. also, i like poking around in history books. (~_^)

    afaict, eastern europeans began outbreeding (i.e. avoiding cousin marriage) much later than northwestern europeans, and even when they did, they cheated a lot (didn’t follow the church’s regulations — see here and here for instance). they also barely experienced (bipartite) manorialism compared to western europeans (stay tuned for my forthcoming series of posts on manorialism!). thanks to the differences in these two selection pressures between west and east europe, there are major differences in corruption, civicness, family size, individualism, etc., between the two regions — imho!


  29. Jayman: Existing data contradicts this theory, no need to repeat myself on this. I certainly would like to see better data too.

    Hbd chick: ”There are major differences in corruption, civicness, family size, individualism”

    I don’t except Balkans to be like NW Europe but i am not sure about places like Czech Republic, Poland, Baltics and if they can get out of Russia’s orbit maybe Belarus and Western Ukraine too. Estonia is already a first world country. I think these places will probably become more like NW Europe as they develop after Soviet rule just like China is going to be more like Hong Kong. Thanks for the discussion.


  30. @cpluskx – “Existing data contradicts this theory…”

    no. the existing genetic data are too patchy and incomplete at the moment to support or contradict the theory.

    the existing historic data strongly support it. (^_^)


  31. This is fascinating. When I did the DNA test the results showed me to be way in the bell curve’s tiny part. Apparently my family has a lot of fixed mutations and no immediate genetic matches have yet been found.

    Looking closely at my ancestors I found cases of endogamy (not saying incest, mind you!) that were cleverly obfuscated apparently due to a disapproving attitude of New Worlders towards cousin marriage. My great-grandfather from Kishinev, for example, only had two grandparents, meaning he was the result of a double-cousin marriage. Not sure what that means genetically, but I suppose it is the equivalent to sibling mating. Except that double-cousin gigging is halachically allowed. That family had numerous children and no genetic defects ever surfaced. There is evidence that they were from Crimea, where incest was never a crime (pardon the alliteration).

    In addition, there is the possiblility that Crimean Jews (ranging from Krymchaks to Karaites) rejected halachah and so there was no religious proscription against incest. Unfortunately being a Crimean Jew was such an embarrassment that many hid their place of origin and masqueraded as Moldovan, Lithuanian or Ukrainian. An exhaustive study into Jews and endogamy would have to reconstruct the Crimean genetics out of scant evidence and plenty of misdirection. As far as I know there is no such project.


  32. @gnarlodious – “When I did the DNA test the results showed me to be way in the bell curve’s tiny part. Apparently my family has a lot of fixed mutations and no immediate genetic matches have yet been found.

    oh, neat! that’s very cool! (^_^)

    @gnarlodious – “My great-grandfather from Kishinev, for example, only had two grandparents, meaning he was the result of a double-cousin marriage. Not sure what that means genetically, but I suppose it is the equivalent to sibling mating.”

    ah ha! that’s interesting. probability says that double first cousins are as related to one another as half-siblings, so matings between such pairs are not as close as full siblings. (double first cousin marriages happen at rather high frequencies in the arabized world, btw.)

    @gnarlodious – “That family had numerous children and no genetic defects ever surfaced.”

    well, that’s the thing: inbreeding in and of itself does not lead to genetic defects. it’s just that inbreeding (close matings, like cousin marriages) can focus genetic defects in a lineage should they appear. so if there weren’t any genetic defects in your family line, should’ve been fine for them to mate with cousins. this is how we get thoroughbred horses, after all! (~_^)


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