“In One Person” has many of the things that one expects from a John Irving novel: it is set, mostly, in northern New England; its protagonist is a novelist; there are no bears, but there are wrestlers and a prep school; German is taught and spoken, and Austria is visited; there are big questions about the narrator and novelist Billy Abbot’s father, who has been more or less absent since Billy’s birth; there’s lots of sexual awakening and questioning and questing, lots of gender bending, lots of sex.