Originally Posted by
mfckrz
That doesn't say what you think it does, has nothing to do with mixed race.
It's about avoiding cousin marriage—Europeans and East Asians have had various proscriptions against it since ancient times. No doubt part of why their IQs are higher than everybody else.
Certain SNPs related to higher intelligence also exist in those populations with much greater frequency—especially relative to Subsaharan Africans. Mix an SSA with any higher-IQ person and resulting offspring's IQ will be lower than the latter.