EBarnacle here.

In reference to the discussion of racism, there was a 50's SF story entitled, I believe, "My Lady Greensleeves," with much the same theme, in which the punch line was "What's a Jew?" The implication is that humanity always seems to find a way to set up discriminatory practices based on class, color or something. The best we can do is go after these artificial sets of prejudices, one by one, and hope for the best. The author may have been Leinster or Sturgeon.