Heredity, race, and society.

  • Leslie Clarence Dunn
Date:
1947
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Heredity, race, and society. Source: Wellcome Collection.

    59/148 page 57
    less than that of a grand slam at bridge. But different grandchildren (who are brothers or sisters among them selves) will be likely to inherit somewhat different sets of genes from each of their grandparents. Each of the great-grandparents contributes on the average of the genes of each of the great-grandchildren. Here again variations will occur. A great-grandparent may con tribute either more (up to i/ 2 ) or less than y 8 (down to none). What proportion of the genes of a grandparent or a remoter ancestor will survive in his descendants will depend entirely on chance and in no way on the ancestor's bodily strength or weakness, virtues or sins. According to the refuted blood theory of heredity, we inherit y 2 of our hereditary endowment from each parent, 14 from each grandparent, y 8 from each great- grandparent, etc. This idea has taken such firm root, not only in the popular imagination but even in biolo gy, that even now one still hears and reads of a person having 14, ]/s, or some other fraction of blood of some particular race or individual. The most cherished pride of many people is the supposed fact that some fraction of their blood is derived from a noble an cestor, or from a passenger on the Mayflower, or from a real or a trumped-up great man or woman. We can see how preposterous such claims are. To be sure, an individual receives on the average i/£ of his genes from each grandparent, l/g from each great-grandparent, etc. But this is only a statistical average, and in reality one may have either more or fewer, down to no genes at all, especially from the more remote ancestors. More important still, all the qualities of our ancestors were not necessarily due to their genes. And even if they were, then the important thing may have been a par ticularly lucky combination of genes. Such a combina tion is quite unlikely to remain intact in the heredity even for one generation, let alone for many, because the mechanism of heredity is to produce recombinations of the different genes which are so numerous that they are unlikely to repeat. Even some serious writers have failed £0 understand this and have deluded themselves into
    digitised image 1
    digitised image 2
    digitised image 3