A first study of the statistics of insanity and the inheritance of the insane diathesis / by David Heron.
- Heron, David
- Date:
- 1907
Licence: In copyright
Credit: A first study of the statistics of insanity and the inheritance of the insane diathesis / by David Heron. Source: Wellcome Collection.
Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.
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![(8) Fertility of Insane Stocks. In 331 families or sibships* containing at least one insane member, the gross fertility distribution was found to be as follows : Table XXI. Fertility of Insane Stocks. Size of Family 1 2 3 4 6 6 7 8 9 10 11 12 13 14 15 16 Total No. of Families 16 48 44 34 51 35 39 39 21 11 11 6 6 1 1 ] 331 The statistical constants of this distribution are as follows : Mean Size of Family = 5-97 + -ll. Standard Deviation =2-93+ -08. The fact that insanity is a disease of adult life makes us fairly certain that the above families are practically completed. The stocks being middle class, we see at once that the fertility is high, and this is to be emphasised because no limit of duration of marriage has been taken, and no limit to the ages of parents upon marriage. Pearson, dealing with fertile English marriages, begun when both parents were at or under 35, and lasting at least 15 years has found an average gross family of 658, or only about half a child more than in the case of these marriages of insane stock, which may have, and undoubtedly have in certain cases, been started after 35 and have lasted less than 15 years. From the above result it will be clear that insane stocks are as fertile as and possibly more fertile than any other stocks in the community. Even more important than the fertility of insane stocks is the fertility of marriages in which one parent has at one or other time been insane. From Dr Urquhart's data we find 87 such cases, in 48 of which the father, and 39 of which the mother, has been insane. The actual distribution of these 87 families is given in Table XXII: Table XXIT. Fertility of Insane Persons. Size of Family 1 2 3 4 5 6 7 8 9 10 11 12 18 Frequency 5 13 9 14 12 8 8 4 5 7 2 From this we find: Mean Size of Family = 5' 18 + '21. Standard Deviation =2*84+ '15. ' Now 5 18 is precisely the value found by Westergaard for the professional classes in Copenhagen in the case of marriages which have lasted at least fifteen years and for a race more fertile than the Scottish. We have also to remember (i) that the * This word is used in the sense of groups of brothers and sisters the offspring of a single pair.](https://iiif.wellcomecollection.org/image/b21295608_0028.jp2/full/800%2C/0/default.jpg)
