That's it really - but it is a point most people seem to miss.
People don't spontaneously and en masse pick-out their cousins from all others as marriage partners; nor will people marry their cousins above all others without powerful carrots and sticks.
*
Of course I am referring to cousin marriage as a societal norm - and certainly not to each and every individual instance of cousin marriage - obviously some cousin marriages are spontaneous love matches. But most are not when it is the societal norm.
*
And whether spontaneous love matches are the best basis for marriage as a social norm is another question again - maybe arranged marriages, and coercive marriages are better overall? Certainly there are strong arguments on that side.
*
I'm just saying that cousin marriage as a societal norm is inevitably achieved by social mechanisms that are arranged and coercive.
*
P.S - I won't be publishing comments for this post.
*