^Probably depends on the story they are telling and whether or not they would fit that story.
Then again, given how much care, currently, Marvel Studios is putting into these adaptations in how closely the characters mirror their comic counterparts (generally speaking), they might just omit Quicksilver and Scarlet Witch altogether given their direct connections to the X-Men
Then again again, they could just use the "We're meta-humans!" and ignore their parents.
This is assuming, of course, that 20th Century Fox doesn't own the rights to the characters.