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Darwin Correspondence Project

To James Crichton-Browne   5 January 1874


Jan. 5, 1874.

My dear Sir

If you should think the subject of which I wish to speak in this letter important, I wish earnestly to beg your assistance.

My son Mr. George Darwin, who is a good mathematician (having been Second Wrangler at Cambridge)1 has taken a very great deal of trouble in trying, by several independent methods, to discover what proportion of all marriages are marriages between first cousins; and he now feels pretty confident that his results will not be subject to an error of more than 1 per cent. He wishes to utilise these results by the discovery of the proportion of the offspring of first cousin marriages amongst the insane, deaf and dumb, and blind, &c.2 I have for 30 years been desirous of seeing this point determined, and it still seems to me of high importance. We have here, I think, the rare case of an inquiry, the answer to which will be valuable, whatever it may be:—for we shall thus be informed either that such marriages are injurious, or that we may persevere in them with impunity. I have been consulted more than once on this point, but could only say that on general principles it seemed best to avoid such marriages.

Now if you are willing to give your invaluable help, would it be possible for you, by means of your assistants to ask the patients in your asylum whether their parents were first cousins or not, and to record the answers. I presume the questioner would be able to a great extent to judge of the sanity of the answer; and you will doubtless be the best judge of how it will be expedient to approach the subject with them so as neither to rouse their suspicions, nor to give the question a leading turn. Can you suggest any energetic and obliging doctors having the care of the insane, deaf-mutes, blind, &c., who, if I were to use your name, as an introduction would perhaps be inclined to aid my son. I shall be in London shortly, and shall call on Dr. Maudsley and speak to him on the subject.3 If I knew the address of Dr. Nichol (who helped me on ‘Expression’) I would write to him too; and I shall write to Dr. Lauder Lindsay, Dr. Scott of Exeter, and the Rev. Mr. Blair of Worcester—and I have good hopes from their former obliging conduct to me, that they will be willing to help.4 These names form my list. Now will you have the kindness to think over my son’s proposed investigations and aid him with any suggestions which may occur to you, and if you possibly can with detailed information about your patients. From your repeated acts of kindness to me I feel sure that you will forgive my troubling you at so great length.

Pray believe me my dear Sir | Yours very sincerely | Charles Darwin.


George Howard Darwin was ‘second wrangler’ at Cambridge in 1868, that is, he was second in the final examination for the mathematical tripos (Cambridge University calendar 1868).
CD had tried unsuccessfully to have a question about cousin marriages added to the 1871 census (see Correspondence vol. 18, letter to John Lubbock, 17 July 1870). George had written an article based on his earlier investigations, ‘On beneficial restrictions to liberty of marriage’ (G. H. Darwin 1873a). He published his later researches in an article on cousin marriage in 1875 (G. H. Darwin 1875a).
CD was in London from 10 to 17 January 1874. It is not known whether he met Henry Maudsley then.
CD referred to Patrick Nicol, William Robson Scott, and Robert Hugh Blair in Expression, pp. 14, 61–2, 185–6, 311–12, and 352. In G. H. Darwin 1875a, p. 165, George credited in particular Crichton-Browne, William Lauder Lindsay, Maudsley, and Scott for the ‘extraordinary vigour’ with which they took up the subject.


Requests help for George Darwin’s investigation of marriages of first cousins. Seeks to determine proportion of first-cousin offspring among the insane, deaf and dumb, blind, etc.

Letter details

Letter no.
Charles Robert Darwin
James Crichton-Browne
Sent from
Source of text
DAR 143: 347
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9227,” accessed on 19 April 2019,

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