| TABLE XVII. | |||
|---|---|---|---|
| Parentage. | No. of fertile marriages. | No. of children. | Ave. to fertile marriage. |
| First cousin. Gene. | 125 | 672 | 5.4 |
| First cousin. Cor. | 150 | 759 | 5.1 |
| Double cousins and uncle-niece | 9 | 39 | 4.3 |
| Other consanguineous | 333 | 1605 | 4.8 |
| Non-related | 676 | 3417 | 5.1 |
| Ch. of 1st cousins | 294 | 1395 | 4.7 |
| All consanguineous | 617 | 3075 | 5.0 |
| All non-related | 970 | 4812 | 5.0 |
The report of Dr. Bemiss, and the report of the Ohio commission[[47]] which he quotes, give the following figures:[[48]]
| TABLE XVIII. | |||
|---|---|---|---|
| Parentage. | No. of fertile marriages. | No. of children. | Ave. to fertile marriages. |
| 1st cousins or nearer[A] | 660 | 3363 | 5.0 |
| More distantly related | 119 | 572 | 4.8 |
| Non-consanguineous | 125 | 837 | 6.7 |
| Ohio consanguineous | 155 | 1021 | 6.6 |
| Ohio non-consanguineous | 200 | 1375 | 6.9 |
| [A] Includes double-cousins and uncle-niece marriages. | |||
The comparatively low averages of the consanguineous marriages from Bemiss may easily be accounted for by the fact that the cases were highly selected so that nearly one-third of the children were in some way defective, and the parents in many cases were far below the average in vitality. The "more distantly related" are in a still lesser degree representative of the class, since out of a greater possibility of choice a smaller number were chosen. The "non-consanguineous" were supposed to be near the average in vitality and fertility.
In Norway, according to Uchermann, the consanguineous and the non-consanguineous marriages are equally fertile, averaging 6.1 children per marriage;[[49]] and in a Black Forest village Tenckhoff found an average of 4.6 children to each consanguineous marriage as against 3.5 to each non-consanguineous marriage.[[50]] In regard to the youthful death-rate among the offspring of consanguineous marriages, comparison with non-related marriages is more feasible. I have counted in each case all those children who are known to have died under the age of twenty. This age was taken for the sake of convenience, and to include all children indefinitely specified as having "died young." The results are given in Table XIX:
| TABLE XIX. | |||
|---|---|---|---|
| Parentage. (Genealogies.) | No. of Children. | No. dying under 20. | Per cent. |
| First cousins | 672 | 113 | 16.7 |
| Other cousins | 1417 | 211 | 14.9 |
| Ch. of 1st cousins | 825 | 103 | 12.5 |
| Non-consanguineous | 3184 | 370 | 11.6 |
| (Correspondence.) | |||
| First cousins | 759 | 88 | 11.6 |
| Other marriages | 829 | 71 | 8.6 |
If the figures in Table XIX are to be accepted at their face value, and there seems to be no good reason for not doing so in the genealogical cases at least, the youthful death-rate among the offspring of consanguineous marriages far exceeds the average. The average in the correspondence cases is undoubtedly too low, as many correspondents failed to report the deaths. From the fact that a comparatively large percentage of these were reported as defective, we should expect a higher death-rate than among the unbiased genealogical cases.
Dr. Bemiss found a very high death-rate among the children of consanguineous marriage, due partly to the fact that his cases were reported by physicians. He reports that of the offspring of marriages between first cousins and nearer relatives, 23 per cent "died young;" of the offspring of more remote consanguineous marriages, 16 per cent; and of non-related marriages 16 per cent. There is, therefore, a strong indication of lowered vitality as a result of consanguineous marriage.
A determination of even the approximate percentage of degenerate offspring resulting from marriages of consanguinity by direct inquiry is exceedingly difficult. The average human mind is so constituted as to exaggerate unconsciously the unusual in its experience. Herein lies the fallacy in the work of Dr. Bemiss. His material was "furnished exclusively by reputable physicians in various states," and of the 3942 children of consanguineous marriages in the cases thus furnished him, 1134 or 28.8 per cent were in some way "defective." Of these, 145 were deaf and dumb, 85 blind, 308 idiotic, 38 insane, 60 epileptic, 300 scrofulous and 98 deformed. It is evident that a physician in reporting such data to a physician would naturally give cases in which something pathological existed. Even if there were no conscious bias, such cases would be the ones with which a physician would be most likely to come in contact. Dr. Bemiss himself recognized the possibility of this bias. To quote him:
It is, natural for contributors to overlook many of the more fortunate results of family intermarriage, and furnish those followed by defective offspring and sterility. The mere existence of either of these conditions would prompt inquiry, while the favorable cases might pass unnoticed. Contributors have been particularly requested to furnish without prejudice or selection all instances of the marriage of consanguinity within their various circles of observation, whatever their results.[[51]]