Some parents pass on more mutations to their children than others. Everyone is a mutant but some are prone to diverge more than others, report scientists. A new study shows the number of mutations a child has compared to her parents varies dramatically with some people being born with twice as many as others, and that characteristic runs in families. Source 9z.
It is known that inter-racial parents pass less mutations/defects to their children due to the cross-breeding effect.
Parents from the same racial/ethnic background pose a higher risk is passing the same mutations/diseases which were passed down by their parents.
Hence Hitler's 'Perfect Race' is actually resulting in the reverse effect of perfection (In terms of genetic mutations/diseases).