September 22, 2009
Joseph M. Strayhorn MD
11676 Perry Highway SUITE 1200
Wexford, PA 15090

Dear Dr. Strayhorn:

The internet is full of the news that you opine that conservative religious communities are more successful at discouraging condoms than discouraging sex.  Call me a heretic, but I opine that there is more to fertility than condoms.  In fact, this will have you reaching for yours stake, fagots (that’s bundles of sticks) and Ronson ligher for the usual heretic treatment, there is more to fertility than sex and condoms combined.

There was a study done a few years ago in which they compared population density with population growth rate among over a thousand studies of wild animals.  What they found for most of the studies was this.


The curve has a distinctive shape, but crudely put, the lower the population density the faster the growth.  That translates inevitably to, “The closer the kinship, the greater the fertility.” 

Can we assume, just for arguments sake that bunny rabbits don’t usually use condoms?  At least not often enough to be statistically important.  They don’t attend religious services often, either, do they?  Lie to me if you have to.  Say rabbits don’t go to church. Also, the curve shows no effect of environmental saturation.

So if you are going to talk about birth rates, you are going to have to take that study into account.  The study is not going to go away.  They exhausted all the suitable field studies of animals in the professional literature.  In animals the “closer the kinship the greater the fertility” is fact and will stay fact for a long time.  

The same phenomenon has been demonstrated in humans in two different studies.  The statistics showed no visible effect of choice.  That is not to say there is no choice.  It is to say that the effect of choice is vanishingly small compared with the effect of kinship.

So anybody who is going to talk about human birth rates has to take those studies into account explicitly.  Otherwise the homework has just not been done.  No opinion can be taken seriously.

So before invoking condoms, you need to read the articles.  The other two are An Association Between Kinship And Fertility of Human Couples.  Agnar Helgason, Snaebjoern Palsson, Daniel F. Guobjartsson, Pordur Kristjansson and Karl Stefanson, SCIENCE vol 329 8 February 2008 and Comment on “An Association Between the Kinship and Fertility of Human Couples,” Rodrigo Labouriau and António Amorim, SCIENCE vol 322 12December  2008.  Then you need to go back and look at your data and ask, “Does what we know about fertility account for what we see here?”  In other words, do the societies that have a higher degree of religious conservatism also have more close knit communities?  Do they tend to stay near home, marry into families that have lived near their own for generations, and have a higher likelihood of marrying a cousin out to sixth cousin or so than societies where they go off to college to look for a spouse, where they marry outside their own church or where they have no church at all? 

I would say obviously yes, but it is your data.  You need to make that call. 

Insufficient fertility is essentially wiping out the affluent people in the affluent countries.  By addressing the issue of kinship and fertility explicitly, you could be part of the solution.

If you want more evidence, it is posted on where I also plan to post this as an open letter.  That way you never have to worry about losing it.

I hope you will take this important matter to heart.  I know that genetics is not your field, but you have already committed yourself in public, so you are honor bound to find the truth if you possibly can and then spread the word. 


M. Linton Herbert MD 

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