X-Men

What are Mutants?
Mutants are a small percentage of the human population who are carriers of the mutated X-gene that gives them superhuman abilities. Mutants are distrusted by the majority of the public because of the mutants'(or at least the majority of them) inability to control their powers. Mutants began to emerge in the late 1980s and early 1990s.

The Xavier School
Professor Charles Xavier--a mutant rights activist and secretly a powerful mutant telepath himself--transformed his family estate in Massachusetts into a school for young mutants to gain control of their powers and continue their normal education.

Formation
After the formation of the Avengers, Xavier decided that the world needed a mutant super-team so the public could see mutants standing for protection of everyone in an attempt to improve mutant-human relations.