Quicksilver and Scarlet Witch were originally the Romani children of Romani parents Django and Marya Maximoff. Ten Marvel started messing with their history so that it was believed they were the children of Magneto and his then-wife Magda, Magda leaving Magneto before their birth, taking sanctuary with the High Evolutionary. Magda fled again, dying of exposure, with the High Evolutionary giving the children to the Maximoffs.
And then Magneto discovered he was not their father after all.
So who was? Well, the preview of next week's Uncanny Avengers #4 reveals a fair amount…
So basically, after all that, they are once again as they once were, back in the beginning with their original parent, with a little genetic alteration courtesy of the High Evolutionary?
Seems so. And, officially, no longer mutants.
So Fox can't have them for any more X-Men films… and Marvel Studios can. And as for Magneto? Who knows….