In his early attempt at creating the super human, Hitler believed that the Supreme "Aryan" was physically aesthetic and borne from the single white race. So he measured (and excluded) those who fell into his principles.
Since our knowledge of DNA has improved it has emerged that Hitler was right in a way. There is a genetic superior peoples, though he would be shocked to find out that they are the "mixed races". The principle being that the more genetically mixed you are the more genetically superior you tend to be. So taking two distant races, one West European and One Central African you indeed increase the "hetrozygosity" of the individual. Thus the ability to combat diseases is more efficient than one drawn from a single DNA pool (homozygos).
Wikepdia defined Zygosity as >
Zygosity is the degree of similarity of the alleles for a trait in an organism. If both alleles are the same, the organism is homozygous for the trait. If both alleles are different, the organism is heterozygous for that trait. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous.
