The chance acquisition of George, a very rare male calico kitten, sent Laura Gould on an unexpected and lengthy odyssey into the history of genetics. She thought she remembered that all calico cats were female. But why was that? And how did the rare exceptions like George occur?

Gould's curiosity about her new cat's existence caused her to learn some basic genetics, to examine its history, and to explore cat folklore. The result is a thoroughly enjoyable and not too technical book narrated with inimitable grace and wit.

In this story of an unrecognized chapter in the history of science, Gould takes us from ancient theories about inheritance and sex determination, through Mendel's famous experiments with his round and wrinkled peas, to speculations by Darwin and others about the rare male calicos. The struggles of early twentieth-century scientists to find and study rare male calicos in the hope of answering fundamental questions in the newly emerging field of genetics are explored in amusing detail.