In Mary, he sees a sinner like himself—a friend of Christians, but a black sheep.
But Bowie rarely spoke about the black sheep in his family, who spent most of his adult life in a mental institution.
by 1822 in figurative sense of "member of some group guilty of offensive conduct and unlike the other members," supposedly because a real black sheep had wool that could not be dyed and was thus worth less. But one black sheep in a flock was considered good luck by shepherds in Sussex, Somerset, Kent, Derbyshire. Baa Baa Black Sheep nursery rhyme's first known publication is in "Tommy Thumb's Pretty Song Book" (c.1744).
A person who is considered a disgrace to a particular group, usually a family: “Uncle Jack, who was imprisoned for forgery, is the black sheep of the family.”