[bonzini]

Well, they are all Europeans. I am not denying that racism existed at the time, but hardly any non-white person lived in Europe back then. (Even nowadays in most European countries the percentage of non-white people is so low that, in a group of 30, finding none is well within statistical error).

[BerislavLopac]

Interestingly, many (if not most) of people on that conference were Jews, which were often treated as second-class citizens even before Hitler.

Also, an additional testament how Marie Curie was exceptional was that she was an immigrant from Poland (which didn't even exist when she was born; her initial studies were in secret), and that she is still the only person ever to win two Nobel prizes for two separate fields (physics and chemistry).