Mutation is more subtle and complex than most of Cook's novels. He employs an omniscient narrator and the reader can see into the characters' minds and learn why they think and act as they do, but character development continues to be subordinated to plot. Victor Frank, although somewhat unbelievable in the secret manipulation of his child's genetic material, is realistic in his slow change from pride in his creation to anguished horror at what he has wrought.

Cook opens his novel with an epigram from Mary Shelley's Frankenstein (1818), and not only borrows the theme of the over-reaching creator, but also the name of her character, Victor Frankenstein.