Since When Can Kitty Pryde Send People Back In Time?
Good question with no obvious answer either given or implied in the course of the film. The narrative answer, as previously stated by screenwriter Simon Kinberg and director Bryan Singer, is that using Kitty as the method of sending Wolverine back in time was an homage to the fact that it was Kitty who did the time travelling in the original comic book story. But really, like the whole thing with Professor X being alive, Magneto having his powers, and Wolverine’s claws being re-adamantiumated, it’s just one of those things you have to go with in order to enjoy the movie.
But if you’re one of those obsessive types who absolutely, positively has to have a definitive answer about these things, there might be something we can offer. In the Grant Morrison run on X-Men, the idea of secondary mutation was introduced. This meant that a mutant can be born with one ability, like making oneself intangible, and then they can later develop a separate, second ability, like sending other people’s consciousness back in time.
X-Men: First Class established the precedent by giving Emma Frost both her comic abilities: telepathy and transforming her skin into a diamond shell. From the sounds of it, as Kitty describes her time travel ability to Professor X and the others, it seems like a new thing to her, and them.
So let’s just say “secondary mutation” and leave it at that.