Unlike other Asimov characters, Baley has a past. His father had been a nuclear physicist with a rating in the top percentile, who was declassified because of an accident in the nuclear plant where he worked. Baley's mother died early, and his father died when Baley was eight. Baley remembers him as sodden, morose, lost, speaking sometimes of the past in hoarse, broken sentences. Baley and his two older sisters went into the Section orphanage. Baley knows the horror of declassification, and that knowledge motivates his desperation to solve the mystery rather than go through what his father suffered. Also
unlike other Asimov characters, who are individuals isolated by job or temperament, Baley has a family: a wife, Jessie, who had enjoyed a small, wicked pride in the name Jezebel until Baley told her that Jezebel was not a painted hussy, and a son, Bentley ("Ben"). Baley also has experiences that keep flooding into his mind: the childhood games of running the strips and hide-and-seek with guide rods (whose gradual warming leads visitors toward their destinations), an uncle who worked in Yeast-town (once Newark, New Brunswick, and Trenton) and gave him illegal yeast treats when he was a child.