After she accidentally adopted a calico cat that turned out to be a male, Laura Gould was seized by curiosity. For there to be no male calicos at all would be understandable - it was their extreme rarity that was the puzzle. Gould, an expert in linguistics with no previous training in genetics, decided to learn how this could be. Her researches took her through the great discoveries in genetics, from Mendel's studies of inheritance in peas through...