The whole "blonde haired blue eyed" thing about Nazis is largely a result of propaganda, shitty textbooks, and general spreading of false information more than a basis in fact.

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The Nazis did not kill people because they WEREN'T blonde hair and blue-eyed. The blonde blue eyed Aryan featured in propaganda because it was seen as an ideal, but I'd say this ideal was also pretty dominant in the US as well, and for quite a long time. As you well know, top Nazis like Hitler and Goebbels did not look like the Nazi ubermensch poster boys, and it was not a big deal that they didn't. The Aryan Superman you see in images like this ( http://i.imgur.com/X0pqaHl.jpg ) is an ideal to aspire to, and meant as a contrast to the 'lesser races', but it wasn't a standard mold that one had to fit into.

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The Nazis were totally cool with people not fitting the 'look'. Part of their whole animosity towards Jews was the idea that Jews COULD look just like "you or me", and that they were infiltrating and poisoning society. That the Nazis also played up in their own propaganda a caricature of a Jew, with the stereotypical giant nose and curly dark hair doesn't mean that they believed it was the only way a Jew could look.

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An Aryan-looking Jew would have some advantages in that they would be less likely to come under suspicion from their looks alone, but this was not enough. Jews were known by their associates, neighbors, and records, so it was usually possible to ascertain someone's Jewishness without them fitting the stereotypical image. Looking Aryan would not save them if they were found out. They would be killed just like the others.