With Disney’s acquisition of Fox, many Marvel fans are speculating as to how the Fox-owned characters, including the mutants and the X-Men, will make their debut appearance in the Marvel Cinematic Universe. Theories run wild, from alternate timelines and even more time travel to Scarlet Witch manifesting the mutants into reality.
A more simple and plausible explanation exists for the case of the X-Men appearing on an established timeline that has so far seen no mutants: the multiple snaps on Earth that occurred during Avengers: Infinity War and Avengers: Endgame were directly responsible for bringing mutants into the MCU.
In Avengers: Endgame, Rocket says that as a result of the Thanos’ snap, “Earth became ground zero for a power surge of ridiculously cosmic proportions. No one’s ever seen anything like it.” The events of Avengers: Infinity War left Earth as the epicenter of the largest power surge in history, and during Endgame, Earth experienced another two snaps, with each emitting a significant amount of radiation and energy.
Before he brings everyone back, Hulk notes the radiation resulting from the snap is mostly gamma. Given that gamma radiation is what gave the green giant his powers, it’s not too farfetched to think that exposing others to gamma could also trigger the development of superpowers. Another possible energy source that could trigger a mutation could be emitting from the Infinity Stones themselves.
This theory is even more convincing when one considers that we have actually seen the Infinity Stones give people abilities. Scarlet Witch and her brother, Quicksilver, were given their powers due to exposure to the Mind Stone within Loki’s scepter. Carol Danvers also received her powers from the Tesseract, which houses the Space Stone.
With the entire Earth and beyond being exposed to the power of the Stones during the snap, there is bound to have a major effect on its inhabitants, especially when the planet experienced that level of cosmic energy spikes three times. It would have a bigger effect on some people than others, and for those who develop abilities, the MCU could possibly introduce the X-Gene as an explanation. In the comics as well as the 2016 film Deadpool, it was shown that many people are able to keep their X-Gene repressed, and the energy resulting from the snap could be just enough to trigger the gene into action.
This theory could also work without changing the backstories of the characters too much. Before the snap, mutation could just be a rare occurrence in the population, allowing for a small number of mutants such as Charles Xavier, Magneto, Cyclops and Wolverine to have existed prior to Thanos’ arrival. As far as why they never intervened in any of the other film’s events, it can easily be said that the original X-Men team was most likely very small and existed mainly for self-preservation.
With more mutant cases rising after the snaps, the MCU could very easily introduce William Stryker as part of a government initiative to research the X-Gene. The increasing experimentation on mutants could lead to future storylines such as Weapon X and X-23. With Ryan Reynolds expected to work with Marvel Studios on the third Deadpool film, the reactions of the MCU’s inhabitants to widespread Mutants could possibly allow for Deadpool to maintain most of his origin story from the first film without too many contradictions.
There have been little official updates on the status of Mutants in the MCU, although Marvel Studios President Kevin Feige teased their appearance at Comic-Con last year. Fans continuously come up with ideas and theories for how to bring one of Marvel’s most famous teams to the MCU with a similar theory from last year that suggests that both the Eternals and mutants are connected through the Infinity Stones. With the Stones being such a powerful object in the MCU, it is a definite possibility that using them so significantly on Earth three times could have triggered the development of Mutants.
The events of Avengers: Endgame may have resulted in the creation of mutants in the Marvel Cinematic Universe.