On the marriage of first cousins / by Ethel M. Elderton.

  • Elderton, Ethel Mary.
Date:
1911
Catalogue details

Licence: In copyright

Credit: On the marriage of first cousins / by Ethel M. Elderton. Source: Wellcome Collection.

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    individual occurring is 200 to 800 times more likely among the offspring of cousins than of non-kin. It will thus be seen that Mr. Jacob’s results confirm in rough outline, at least for one popular theory, the results of observation. The real danger of cousin marriage lies not in the existence of patent defects in the stock. Nor can we recommend cousin marriage because the stock has certain patent valuable charac- teristics. Behind the obviously advantageous quality may exist the rare but latent defect. The danger of cousin marriage lies in the probability that the germ- plasm of each individual contains numerous latent defects, each of which is rare in the community at large, and each of which is of small danger to the individual or the offspring unless the mating is with another individual whose germ-plasm contains one or more of the same latent characters. It is perfectly true that the study of an ample pedigree, extending for five or six generations with all the col- lateral kin, may enable us to ascertain definitely by patent illustrations the existence in the stock of a latent characteristic. But its non-appearance, even in such an exceptional pedigree, cannot be taken as wholly satis- factory proof of the non-existence of this defect or of other latent defects. And, after an examination of the evidence at present available, we feel justified in asserting that in the bulk of cases cousin marriage is undesirable, even in those instances where the indi- viduals can boast of an apparently normal and healthy ancestry and collateral kinship. The one exception we would make is in the case of the occurrence of some very rare good quality, which is peculiar to a stock, and which cannot easily be preserved for social profit except