X-Men: 10 Theories For How They Can Join The Marvel Cinematic Universe

Eternals promises to delve into thousands of years of MCU history, and there are plenty of theories out there about how the 2021 release could set the stage for mutants to join this shared world. In the comics, the X-Gene was created by The Celestials, a group of ancient cosmic beings who will play a key role in this movie. Needless to say, that could easily be the case in the MCU as well.

Basically, mutants could be a failed experiment before the Celestials created the Eternals, though there's another compelling possibility. In this movie, the heroic Eternals will battle the monstrous Deviants, and mutants could very easily be their descendants, thereby explaining why they don't always look like regular humans (Beast, Nightcrawler, and Mystique, for example).

Of course, that doesn't explain where they've been all this time, but with Eternals set to finally step out of the shadows, perhaps their emergence - and the return of the Celestials - will lead to the X-Gene being "switched back on," thereby meaning mutants become a huge part of the MCU in future.