Mutants in X1 aren’t a new discovery. The public has known about them for decades through isolated events like The Cuban Missile Crisis, JFK’s assassination, Trask’s death, and Xavier’s thesis. For most of the 20th century, to major public, mutants were seen as extremely rare, maybe around 0.1% of the population and their appearances were treated as unusual, one-off cases rather than a broader trend.
From the 1970s through the 2000s, mutant incidents were mostly small-scale and localized, reinforcing the idea that mutants were anomalies, not a political issue. By the 2000s, however, mutant powers began appearing more frequently and more publicly. This shift led politicians like Robert Kelly to reframe mutants as a growing, unpredictable population rather than rare individuals.
In X1, what’s new isn’t the existence of mutants, but the fear that they’re no longer rare, controllable, or safely hidden. That's why just in 2000s comes The Mutant Registration Act.