From their inception, the X-Men have been used as a stand-in for every oppressed and/or feared group in modern culture, but perhaps the most potent is the mutant debate being a stand-in for the Civil Rights movement (that's despite most of the X-Men's biggest hitters being white, but shhh). Across the thousands of comic issues exploring mutant...issues, there have been a handful of controversial parallels between the two, the weirdest being the intimation that calling someone a mutant is akin to using racial slurs. In a seventies issue Kitty Pryde hurled the n-word at a black man who called her a mutie, and recently that unfortunate comparison reared its head again in the pages of Uncanny Avengers, as Alex Summers gave a speech to the world's media on how mutant was a "divisive word" and people should be characterised on what they do, not how they're born. The speech has a lot of problems, but the biggest one for readers to accept is that mutants hate being called mutants. For one thing, it's a scientifically accurate name; for another, most of them label themselves as it without issue; and on top of all that's, it's an uncomfortable parallel. Ah well. Embrace it!