I thought it would be fun to open with the Kennedy assassination, and we reveal that the magic bullet was controlled by Magneto. That would explain the physics of it, and we see that he’s pissed off because Kennedy took all the credit for saving the world and mutants weren’t even mentioned. - Matthew Vaughn
Some might question how tasteful it is to recreate the assassination of President Kennedy, but at least the story is on the right track. The evolution of mutants in the U.S. certainly wouldn't come without casualties.