Actually, there was another stepchild of Darwinism that had specific Communist and Stalinist affinities, and that was Lysenkoism, which suggested that if, say, a fox dipped its tail in cream-colored paint, its offspring would have white tail-tips. This was part of the Communist fascination with control of nurture and thought control. Stalin actively promoted Lysenko and his students, some of whom survived Stalin and had to execute intellectual (and political) climbdowns in the 50's.