The X-Men may be some of the most popular Marvel characters and properties, but in the actual Marvel Universe, mutants have been far from the average Joe's favorites. Since the Bronze Age of Comics, the X-Men and mutants as a whole have been defined by the prejudice their species faces. This treatment has sometimes confounded fans, but it's perfectly explained in a classic miniseries from the 1990s.
Source：https://www.cbr.com/marvels-miniseries-mutant-hate-explained/
