Even amongst pro bodybuilders, there has always been the knowledge that exceptional strength is much more observant in the white ranks.
Whites are built thicker, heavier and more robust. Think Dorian versus Wheeler.
As well, brews tend to have more rounded muscle bellies, which has been shown scientifically to be much less efficient for joint flexion, the be-all, end-all of strength expression.
Blacks have millenniums of ancestry running around in hot weather, eating twigs and berries and building bamboo shacks.
Whites have eaten meat, built structures of wood and stone and lived lives requiring brute strength over fleet-footed maneuverability.
Low bodyfat and muscularity (not to be confused with mass) have little to do with absolute strength.
A white's CNA is superior. Muscle doesn't mean shit if the electronics system is not up to par.