/sci/ - Science & Math

>>15392678
>the major confound being geographical proximity and morphological variation inhibiting mate choice even among those genetically compatible. STILL to do with geographical proximity.
Helgason's 2008 study on 200 years of icelandic marriage and birth records found that geographical proximity was only a proxy for relatedness, they found relatedness the strongest correlate and quite consistent over the generations studied.

I don't dismiss the effect of disease in some cases it clearly plays a role but I find the evidence seems to be there to support a possible mechanism involving group genetic similarity.