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Darwin Correspondence Project

To G. E. Shuttleworth   17 February [1874]1

Down | Beckenham | Kent.

Dear Sir

My son George Darwin (who is a good mathematician, having been 2nd. wrangler at Cambridge) has been at work for nearly a year in trying to discover, by several independent statistical methods, what proportion of all marriages are between first cousins; and he now feels pretty confident that his results will not be subject to an error of so much as one per cent.2 He is being greatly aided in this part of his enquiry by Dr. Farre, the Registrar General.3 He now wishes to utilize these results by the disovery of what the proportion of the offspring of first cousin marriages may be amongst the insane, deaf and dumb, idiotic, blind &c. I have for 30 years considered an answer to this enquiry of importance. We have here, I think, the rare case of an enquiry, the answer to which will be of value, whatever it may be; for we shall either find that such marriages are injurious, or that they may be persevered in with impunity.

Dr. Crichton Brown, who has been at great pains to help my son, has been kind enough to permit me to use his name in introducing myself to you; and he appears to think it very likely that you will consider this enquiry of sufficient importance to be willing to aid my son by asking the patients in the asylum in which you are in attendance, either by means of assistants or personally, whether or not they are the offspring of first cousin marriages, and recording the answers.4 The question which my son proposes to ask is, Were your parents first cousins or not? The questioner will doubtless be the best judge of the most prudent way of approaching the subject, and of explaining the question in each individual case, and would be to a great extent able to judge of the trustworthiness of the answer from the known character of the patient.

If you should be willing to undertake this laborious task you would be conferring a very great favour both on my son and on myself; and I would beg you to send the results to him at Trinity College, Cambridge, where he is a resident fellow.

Would you have the kindness to add a general description of the rank of life from which the majority of your patients are drawn,— e.g. labourers and artizans,— shop-keeper and commercial,—upper ranks.

With apologies for my intrusion on you, | Believe me | Dear Sir | Yours faithfully, | Ch. Darwin

Feb. 17th.


The year is established by the relationship between this letter and the letter from G. H. Darwin, 6 February 1874.
See letter from G. H. Darwin, 6 February 1874. This is one of the letters George wrote for CD to send to people suggested by James Crichton-Browne.
CD refers to William Farr, who had a senior position in the General Register Office; however, the registrar-general was George Graham.
Crichton-Browne’s letters to CD on this subject have not been found, but for CD’s request for his help, see the letter to James Crichton-Brown, 5 January 1874. Shuttleworth was superintendent of the Royal Albert Asylum in Lancaster (Medical directory); his reply has not been found, but George Howard Darwin cited him for the information that five per cent of his patients were the offspring of cousin marriages in G. H. Darwin 1875a.


Medical directory: The London medical directory … every physician, surgeon, and general practitioner resident in London. London: C. Mitchell. 1845. The London and provincial medical directory. London: John Churchill. 1848–60. The London & provincial medical directory, inclusive of the medical directory for Scotland, and the medical directory for Ireland, and general medical register. London: John Churchill. 1861–9. The medical directory … including the London and provincial medical directory, the medical directory for Scotland, the medical directory for Ireland. London: J. & A. Churchill. 1870–1905.


At the suggestion of Crichton-Browne CD writes on behalf of his son George, who is making a study of marriages between first cousins and of their offspring to determine the proportion of the latter who may be among the insane, deaf and dumb, idiotic, blind etc. Is GES willing to ask his patients [at the Royal Albert Asylum] for the information relevant to this study?

Letter details

Letter no.
Charles Robert Darwin
George Edward Shuttleworth
Sent from
Source of text
Wellcome Collection (MS.5134)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9299A,” accessed on 19 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 22