Q2: What is a mutant?
A2: Mutants are individuals born with the X-gene, making them the next possible step in human evolution, Homo superior (as opposed to homo sapiens). While the X-gene is present at birth, it is normally not until puberty that a mutation due to the X-gene begins to fully present itself, and unleash a mutant's full potential. While most often, this is in the form of a physical mutation of little import, but in other cases, mutants can develop a great variety of superhuman abilities due to how their X-gene manifests.
Purportedly, Stan Lee came up with the idea of “mutants” – humans born with a special “X-factor” in their genetic makeup which gave them super-powers – because he had such a hard time coming up with explanations on how the heroes and villains obtained their powers. Of course, this isn't entirely the case. While Namor is considered to be the "first mutant" character at Marvel, and debuted in 1939, he was not called as such until X-Men (vol. 1) #6, in 1963. Other characters with similar origins existed was before Marvel Comics as we know it today even existed, back during the Timely/Atlas days of the company. Among them are the "Weird Woman" who appeared in 1952, in Amazing Detective Stories #11, Roger Carstairs was a mutant illusionist who appeared in Man Comics #28, in 1953, and the first true character called a "mutant" on panel, Vincent Farnsworth, who had a phasing power, who appered in 1959. Prior to the X-Men there was also Lucius Farnsworth, a mutant millionaire beekeeper with size-changing and telepathic powers (possibly an early attempt to create Ant-Man) who appeared in Tales of Suspense #6, in 1963.
It would be in X-Men (vol. 1) #1 that Stan Lee and Jack Kirby would use the concepts of mutants as the crux of an entire story. Mutants were to be the science fiction analogues for a real-world social problem: racism. Other creators who have worked on the X-Men in the years that followed, most notably Chris Claremont, furthered this parallel to make the issues mutants face one of the most relatable to fans in comics.
While the heroes of the Marvel Universe had their share of angst, the mutant heroes had to deal with hatred for “their kind.” Unlike heroes who gained their powers through cosmic rays, special serums, or suits of armor, the general populace was wary of mutants – so called “Homo superior,” especially those who claimed to be humanity’s next evolutionary step. Like humanity supplanted Neanderthals, mutants seemed to be what would replace Homo sapiens, which inspired fear in most of the baseline human populace.