here is a rather long excerpt from a publication from 1891 entitled “Studies in Jewish Statistics, Social Vital and Anthropometric” by joseph jacobs.

i’m cutting and pasting such a large section from the publication because jacobs: 1) recounts the methods and results of g.h. darwin‘s study of first-cousin marriage amongst the english upper- and middle-classes; 2) describes in detail the process he used to come to a figure for first-cousin marriage amongst upper- and middle-class english jews; and 3) because it’s such a delightful read. (^_^)

jacobs concluded that the rate of first-cousin marriage amongst upper- and middle-class english jews was something around 7.5%, roughly double that of upper- and middle-class englishmen and five times that of the average londoner. (jacobs doesn’t have any figures for other classes of english jews.) not sure i’m completely convinced by his methodology — was it right to use the same-name marriage/cousin-marriage rates of the native english as the basis for calculating the cousin marriage rate for english jews? dunno. but it’s a start anyway. seven percent is pretty high for northern europe; but, for comparison, the rates for many (especially southern) regions of italy were well above 10, 20, and even 30% as recently as the early 1960s.

one shouldn’t extrapolate based on the evidence from one country to the whole of europe, but if the situation for nineteenth century jews in other european countries was similar (i.e. they married their first-cousins at considerably greater rates than other european populations), then it’s not surprising that recent genetic studies have found that, within the different jewish populations (like the ashkenazis of europe), the members are genetically similar to one another to the degree of fourth- or fifth-cousins. not strange if they’ve been inbreeding for longer(?) and more recently than many other europeans. plus, as a group, they’re obviously quite endogamous in their marriage practices in general — at least up until recently when the numbers of out-marriages have increased.

without further ado, mr. jacobs [pgs. 2-5]:

“In the many discussions about the alleged evil effects of consanguineous marriage, the Jews are referred to by both parties in support of their views. The assertion is often made and as often denied that Jews suffer more from deaf-mutism, idiocy, etc., owing to the fact that consanguineous marriages are more frequent among them. Yet until we know the proportion of consanguineous marriages among Jews and the proportion of the offspring of such marriages among Jewish deaf-mutes, etc., we cannot establish any causal connection between the two facts. The mere assertion that there are more such marriages among Jews and more of their results among the afflicted classes does not help us until we know how much more. For if there is only the same proportion in the two cases, the relations of cause and effect is by no means establsihed…. It is clear, therefore, that the first stage in any such enquiry is to determine the proportion of consanguineous marriages. This I have attempted to determine for English Jews in the following manner.

“In 1876, Mr. G. H. Darwin, son of the great naturalist, read a paper on marriage between first cousins before the Statistical Society and summarised his results in the ‘Fortnightly Review’ for July of that year. Examining some marriage lists in the newspapers he observed that several occurred between persons of the same surname and on determining the proportion of these ‘same-name marriages’ he found that they occurred in far larger numbers than could occur by chance. By circulars and other means Mr. Darwin calculated that of these same-name marriages 57 per cent were between first cousins. Now, in marriage between first cousins the bride has the same name as the bridgegroom only when she is the daughter of his father’s brother, while there remain the daughters of his father’s sisters and of the maternal uncles and aunts who may likewise form first cousin marriages. It would thus seem that same-name marriages between first cousins form a fourth of such marriages. But there are less paternal than maternal uncles and more paternal aunts than maternal, because father and mother have to be subtracted from their respective families for the purpose of this inquiry. It follows, therefore, that same-name marriages between first cousins form less than a fourth of such marriages, and Mr. Darwin, by some very ingenious formulae calculated that they form on an average only a fifth of all marriages between first cousins. If, therefore, we multiply the number of same-name marriages by 2.85 (= .57 x 5) we should get, on this method, the number of all marriages between first cousins.

“Mr. Darwin applied his method to several classes of Englishmen with the following results:

“In the case of the Peerage Mr. Darwin examined only the same-name marriages between first cousins and multiplied this at once by 5. His method is to some extent confirmed by his results which are what one would have anticipated, the peerage intermarrying most, the landed gentry next, then the upper middle-class and so on.

“It occurred to me that it would be desirable to apply the same method to English Jews and, with the aid of a friend, I examined all the marriages contained in the ‘Jewish Chronicle’ from the beginning of the New Series in 1869 to the present time with the following results:

Thus, it would appear that of all marriages between English Jews, 7.5 per cent are between first cousins, a proportion more than half as large again as that occurring among the aristocracy, and five times as great as the proportion calculated for the inhabitants of London. The result completely justifies the popular impression that Jews marry among their own families more than the rest of the population, and if confirmed by wider induction, may serve as the basis of investigation into that much vexed question, the effects of marriage between near kin.

“Before, however, accepting even this provisional result, it is desirable to take into account an element in the calculation, which Mr. Darwin considered that he could neglect in his investigations, but which may not be so unimportant in the case of English Jews. Finding from one of the Registrar-General’s Reports that one in every 75 Englishmen in named Smith, 1 in 76 Jones, 1 in 115 Williams, and so on, Mr. Darwin calculated that the chance of a Smith marrying a Smith was represented by the square of [illegible], that of a Jones-Jones marriage [illegible] and so on; and adding together all these fractions, the chances of a same-name marriage occuring was found to be only one out of a thousand marriages. This Mr. Darwin neglected, as he did not profess accuracy to the second place of decimals, and, besides, he only considered that 57 per cent of same-name marriages were between first-cousins, the rest being between more distant relations.

“But among Jews it is a familiar fact that surnames are fewer than among the general population, and it remains to be considered how many of the 42 same-name marriages in the ‘Jewish Chronicle’ were due to the greater chances of such unions owing to the paucity of surnames among English Jews. Taking the 4,720 names contained in the Reports of the Board of Guardians for 1889, the Jews’ Hospital for 1878, and the Anglo-Jewish Association for 1877-8 (London, Birminham, Liverpool, and Manchester only), I found the most popular names among English Jews to be the following:

“The proportions given are too high for English Jews in general, since many names recur in the three lists; the lists themselves are not representative of the whole community in point of names, and we should for the present purpose distinguish between double forms, like Isaac and Isaacs. But the names, on the other hand, are drawn from the very class who are likely to advertise their marriages in the ‘Jewish Chronicle,’ and for that reason I accept the above estimate in default of any other. It may be added that the order of most frequent names and approximately the proportions are nearly the same in the longest of the lists — that of the Jews’ Hospital Report. With regard to one name the proportion is still too high. There are special reasons why the name ‘Cohen’ should occur in the reports of two of the above institutions in more than the usual proportion. I am inclined to take the proportion given by the Report of the Anglo-Jewish Association, viz., 1 in 30, as more near the truth. In the largest list of contemporary Jewish names with which I am acquainted — Lippe’s ‘Bibliographisches Lexicon’ — the Cohens, even with the addition of the Cohns and the Kohns, make up only 103(?) out of the 4,600 names, which would give a proportion of about 1 in 45 for Jews in general.

“Accepting the proportions in the above list, we find that without any intermarriage a Cohen-Cohen marriage would occur in every 900(?) marriages if we accept 1/30 as the proportion of Cohens to the general Jewish population. One marriage out of 1,024 would be between persons of the name of Davis, one out of 1,225 between Levys; there would be in the natural course of events one Joseph-Joseph marriage out of every 2,209 marriages and so on. Summing up the squares of 1/900 + 1/1024 + 1/2209 + 1/2704 + etc., we find that about 5 same-named marriages would occur by chance in every 1,600 Jewish marriages, and, therefore, about 8 in the 1,589 examined in the investigation. This would leave only 34 marriages to be accounted for by the method employed above, and we should have instead the of the figures above, 34 same-name marriages out of 1,581, i.e. 2.18 per cent and, therefore, only 6.07 per cent of first cousin marriages, the paucity of surnames among Jews causing a difference of one and half per cent in the percentage of first cousin marriages.

“But against this correction we have to set other factors which in all probability counterbalance it. It frequently happens among Jews that two brothers adopt entirely different surnames, and any union between their offspring would fail to appear among same-name marriages. Further it has become recently the fashion ofr English Jews to remedy the paucity of surnames by adopting others of similar initial, a fashion satirised by the dramatist in calling a Jewish character “Isidore Montmorenci.’ It is probable, e.g., that the name ‘Moses’ would be higher up in the above list if all those who could rightfully claim it had been added to the number of those who still retain it. The children of two brothers, one of whom had adopted a various reading of his name would therefore not come under the category of same-name marriages. In the ten volumes of the ‘Jewish Chronicle’ examined by myself, I noticed 4 such marriages of the ‘Moses-Montmorenci’ type, and doubtless others escaped my noticed by the very nature of the case. Supposing a couple more to occur in the remaining four volumes examined by my friend and only two more the names entirely different to lurk unseen in all the fourteen volumes of the new series, and we would have eight names missing from the list of same-name marriages owing to change of name to counterbalance the eight which might occur by chance owing to the paucity of surnames.

“I am inclined, therefore to reject the correction which seems at first sight due to the few surnames current among Jews, especially as the fractions which give the corrected estimates are probably too large as an examination of the 42 names would show. Only 14 of these marriages are between persons with names from the above list, the remaining 28 having more unfamiliar names, and only 8 are from the first 10 names. Further, we only assume that 57 per cent of these same-name marriages are between first cousins and this constant is by no means certain and may be too low. The percentage of first cousin marriages as originally determined may therefore be still retained and we may say that of every two hundred marriages among English Jews of the upper and middle classes fifteen are between first cousins.

“It by no means follows that the same proportion holds for all the Jews in England. The marriages advertised in the ‘Jewish Chronicle’ are only about one-third of all Jewish marriages in England as given in the Reports of the Board of Deputies. The above conclusions only hold, therefore, for the ‘upper third’ of the Jews in England, the original ‘English colony’ as we may term them. What may be the amount of intermarriage in the large ‘foreign contingent,’ which, probably form the remaining two-thrids it is impossible to say, without consulting the registers of the Great Synagogue. I merely wish to guard against the precipitate conclusion that is likely to be drawn from the above investigation, that all the Jews in England marry their first cousins to the extent of 7.5 per cent in all marriages. It is needless to add the caution that still less do these results apply for Jews universally….

As has been vaguely conjectured but never hitherto proved, English Jews have the largest number of such marriages among all classes of the population.

previously: but what about the english? and jewish inbreeding and inbreeding and the ancient hebrews (and the arabs)

update 09/12: see also inbreeding in nineteenth century alsace-lorraine (including jews)

(note: comments do not require an email. like g.costanza@vandelay.com.)