Another point against the idea that none of the Faerie and/or supernatural stuff really happened are the Murray sisters, identical twins. Bax's mother, Martha, looked to be in her "late forties" (16). His Aunt Thelma was "close to ninety" (244). The math is simple enough, and Martha "spent about forty years" (280) in Faerie as "a sorcerer's wife", where no one ages. I can think no other reasonable explanation for identical twins to be forty years apart in age (without dragging in time travel or really fast spacships).
-Roy