January 18, 2015


Professor Roland Littlewood

Departments of Anthropology and Psychiatry

University College London


Dear Professor:

My father once told me in the context of helping me write a paper, “If you do your absolute best at something you will sometimes find that you have accomplished more than you ever intended too.”  That has not been my experience; I often find that I have accomplished less than I would have thought possible.  But I like the idea.  Maybe if I had better work habits.

I read that you have taken an interest in “Genetic Sexual Attraction (GSA),” or whatever the current term is for the occasion where immediate family members separated at birth fall in love upon reunion years later.  It does not appear to be your greatest interest just now, but you are certainly a major figure in the field.  What I think is that GSA, far from being a dark subject bearing on an infrequent occurrence is the flip side of what is the most important issue of the day.  And you are the expert. 

First, the phenomenon should be no surprise.  Bateson demonstrated it many years ago in Japanese quail, which I suppose we can rest assured are free of the darkest cobwebs of the human psyche. Patrick Bateson Mate Choice (Cambridge University Press Cambridge 1983).  This requires no lengthy explanation.  Fertility is generally correlated with kinship making allowance of extreme inbreeding being bad.  On the Regulation of Populations of Mammals, Birds, Fish and Insects, Richard M. Sibly, Daniel Barker, Michael C. Denham, Jim Hope and Mark Pagel SCIENCE vol. 309 July 22, 2005 page 609.  It works in humans, too.  An Association between Kinship and Fertility of Human Couples Agnar Helgason et al. SCIENCE vol. 329 no. 5864 February 8, 2008 page 813 – 816

So what we are looking at is ordinary garden variety natural selection; a healthy person will seek kindred mate (so long as the Westermark effect is avoided) simply because that is the way to have the most children.  The attraction should be as strong as the attraction of sex itself, since if cousin marriages are eschewed for several generations the whole population dies.  (That requires bringing in more data, but check it out at http://www.nobabies.net/A%20January%20summary%20for%202015.html )

So make yourself familiar with the references and the web site, and the next time the halcyon clarity of your day is troubled by somebody who wants to know about GSA respond airily that it’s all a continuum from pornography through bestiality, homosexuality, marrying strangers and marrying kin each step being more biologically effective than the one before.  You should be able to offend people intensely in great numbers – the one thing that for me goes as my father promised.

Let me know how you fare. 


M. Linton Herbert 

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