In the 90’s X-Men storyline Age of Apocalypse, the son of Charles Xavier, David Charles Haller (a psionic mutant with multiple personalities who went by the name of Legion) traveled back in time to before his father and Eric Lehnsherr, the mutant known as Magneto, had their falling out. Legion intended to kill Magneto before he could become the super villain who fought his father so many times, but instead he accidentally killed his father, altering the timeline and removing himself from existence in the process.
In the altered timeline that resulted, the mad geneticist Nathaniel Essex took the DNA of Jean Grey and Scott Summers and used it to create a perfect mutant, one with psionic powers so great he could kill En Sabah Nur, the mutant madman who ruled that alternate Earth as Apocalypse. When the timeline was reset, Nate escaped that timeline and ended up in the 616 Marvel timeline, where he made friends with Peter Parker and Franklin Richards and even got into a fight with Cable, who was also a mutant bred by Nathaniel Essex (also known as Mister Sinister) by tricking Scott Summers into marrying and having a son with Madelyn Pryor, the clone of Jean Grey.
This is relevant to today’s Queue, I promise.