This series may, intentionally or otherwise, kind of show how children are often more open to weird ideas than adults. The parents and other adults think somethings abnormal perhaps, but in that one special Turi was the one initially pushing that something seemed especially weird. Then Lutz, who admits here that he barely even knew the original girl anyway, was the one who was able to ask something as weird and wild as the old "Who are you and what have you done with X" completely seriously. Even in a world with magic like this one, the whole bodysnatcher type of thing might be a bit crazy sounding.