According to some recent population genetics surveys, around 95% of white Americans (European Americans) have no black (Sub-Sahara African) ancestry. And the 5% of whites who do, seem to have only a trivial amount.
Nonetheless, the average admixture of African Americans seems to be around 80% black and 20% European.
What does this mean?
First, the USA historically has not been a hotbed of miscegenation as Cultural Marxists like to tell us. Your eyes and common sense should tell you that if there were widespread miscegenation, there would be hardly any white Americans but rather large mestizo/mulatto-like populations such as one finds in many Latin American countries (and even there, small white upper classes still exist).
Second, the people in USA tended to cross the color line in only one direction: white —> black. Mulatto people would identify as black and then reintegrate into the black gene pool.
Which brings us to another question, why do mulattoes almost always identify as black?
The standard Cultural Marxist answer to this question is because of culture, such as the one-drop rule. But the reality of the situation belies this half-truth.
The most straightforward answer is what Oxford zoologist Jonathan Kingdon suggested in 1996: black looks are dominant while other looks are recessive. Observation seems to bear this out. A person with only 1/16th black ancestry will still often have visible black characteristics, whereas a white person with 1/16th Japanese ancestry would probably pass for 100% white.
In other words, the reason why most mulattoes identify as black is at least in part biological. Perhaps the white phenotype really is recessive and is easily diminished.
As philosopher Nick Land succinctly formulated: White + Color = Color.
Razib Khan: European Americans have little African ancestry
Steve Sailer: “White Americans are VERY white“