It is not entirely clear when mutants emerged, but their existence was not confirmed until 1976 with the confirmation of Patient W’s Disintegrating Mutant Ability by Dr. Thompson.
Mutants are meta-humans whose abilities which arise from a yet-unidentified gene dubbed the “M-Gene”. The source of this gene is not understood and current theories place its origin with a wide variety of causes. Regardless, the gene has emerged across the world, with scientists noting a slight (but steady) rise in the rate of emergence.
Most mutants are born with little to no evidence of their abilities, but the nature of their powers often reveal themselves in the teenage years (usually coinciding with puberty).
As knowledge of mutants grows, there has been a growth in calls for further government intervention, both in backing research and regulation.