From Frederic Harrison to G. H. Darwin 1 March 1875

My dear Darwin,

There is a subject on which I know you have made inquiries—

Consanguineous Marriage Have you published any results, or arrived at any. I was surprised to find in an article or the P. Mall the other dy, M^r Darwin's opinion [illeg] against the prudence of marriage of cousins. Is this accurate?

I had understood his opinion was—that a simple case of marriage of first cousins, with entire absence of hereditary tendency or disease, when this could be proved was as safe as any other.

I write to ask if you know that M^r Darwin's opinion is the other way, & in any case if your inquiries have led you to form any opinion on that point, strictly within the conditions mentioned.

I have, as you know, some interest in the matter, as my wife & I are children of brothers. My father & her father's family are singularly sound, strong, longlived, & my mother & her mother's family, are as much so—my mother's being exeptionally longlived & diseaseless. (My grandmothers for 3 generations lived to 84, 94, & 90 & had many very sound children.)

Taking that case, do you think there is any extra chance against our children's health?

If you care, I will willingly supply you with my own case. My own opinion is perfectly settled, & not even M^r. Darwin or ""if one rose from the dead"" would it be affected. Our children are perpetually thriving & strong.

If your opinion is made up the other way, do not hesitate to tell me. I am perfectly tranquil on the matter, & only [ful] [curious] when I see the authority of M^r. Darwin reached the other way.

There is of course no hurry about answering this, indeed we can leaveQQQQ it if you like till we meet.  I need not say that what I write is between ourselves.

Yours very truly | Frederic Harrison