I found this gem by Darwin of all people:

"Both sexes ought to refrain from marriage if they are in any marked degree inferior in body or mind"

>>3

>the IQ of the offspring will regress towards the racial average of inferior race.

Indeed.
That's called "regression to/towards the mean"

BTW, this Darwin quote fits Obama to a T:

"I think these authors are right, who maintain that the ass has a prepotent power over the horse, so that both the mule and the hinny more resemble the ass than the horse; but that the prepotency runs more strongly in the male-ass than in the female, so that the mule, which is the offspring of the male-ass and mare, is more like an ass, than is the hinny, which is the offspring of the female-ass and stallion."

lulz