Heredity and eugenics in relation to insanity / by F.W. Mott.

  • Frederick Walker Mott
Date:
[1912]
Catalogue details

Licence: In copyright

Credit: Heredity and eugenics in relation to insanity / by F.W. Mott. Source: Wellcome Collection.

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    Sir Francis Galton, the founder of Eugenics, and to whom the nation owes so much, established the Law of Ancestral Inheritance. According to this law each germ, male or female, contains on an average representative particles or germinal determinants derived from the two ancestral stocks in definite proportions. Thus one quarter comes from each parent, one-sixteenth from each grand-parent, and one-sixty-fourth from each great grand-parent. Thus an inheritance is not merely dual, it is multiple. Galton himself recognised, however, that this law only applied to masses of people and not to individual cases, for he says : “ Though one half of each child may be said to be derived from either parent, yet he may receive a heritage from a distant progenitor that neither of his parents possessed as personal char¬ acteristics.” Again, speaking of Particulate Inheritance, he remarks; “ All living beings are individuals in one aspect, composite in another. We seem to inherit bit by bit this element from one progenitor, that from another, in the process of transmission by inheritance elements derived from the same ancestor are apt to appear in large groups, just as if they had clung together in the pre-embryonic stage, as perhaps they did.” They form what is well expressed by the word traits—traits of feature and character, that is to say, continuous features, not isolated points. The offspring of parents possess a mosaic of inheritance bearing usually a more or less similarity, yet the mosaics of character, whether bodily or mental, are not in any way identical, except in the case , of identical twins. Now, there is a reason for this. Identical twins are the result of fertilization of one ovum containing two germs of identical substance, and this leads me to refer to Galton’s remarkable inquiry into the History of Twins in con¬ nection with Nature and Nurture. He found that similar twins living in a different environment nevertheless remained similar in temperament and character, while dissimilar twins brought up and living in the same environ¬ ment remained dissimilar; these dissimilar twins, however, were the product of two separate ova with dissimilar germs. This shows that every germ has a specific energy of its own, as manifested by a different potential inheritance. Galton also made a statistical inquiry into good and bad tempers, and as a result of this inquiry he says : “It now becomes clear enough and may be taken for granted that the tempers of progenitors do not readily blend in the offspring, but that some of the children take mainly after one of them, some after another, but with a few threads, as it were, of / various ancestral tempers woven in, which occasionally manifest themselves. If no other influences intervened, the tempers in the children of the same family would on this account be almost as varied as those of their ancestors. To recapitulate briefly, one set of influences tends to mix good and bad tempers in a family at haphazard; another tends to assimilate them, or that they shall all be good or all be bad ; a third set tends to divide each family into contracted portions. These facts, ascertained by Galton, are
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