Maaaaagic. Including magic that makes her aging stop in the 20s-ish.
Age:
34
Story:
Mom's in an institution, Dad's a trickster god and the community at large probably thinks that her real daddy is her mama's twin brother. This could be like a sitcom. Anyway, Miranda was raised by Uncle Pietro and got knocked up by Dr. Strange's kid when she was 16. (If someone would play him I'd love you very much.) She's a relatively recent addition to the Avengers after a few years as a paranormal consultant for SHIELD.