American blacks have higher I.Q.s than those in the Motherland because almost all of them are actually mixed race, to one extent or another.
Yes, and that was one of the solutions suggested by Murray and Herrnestein to try to equalize the average IQ between the races - forced intermarriage. In essence elimination of the two races and creating a new single race of mulattos.
Another one was forced sterilization of low IQ blacks.
As I said, neither very politically viable.