English geneticist who, with the English biologist William Bateson (Bateson, William), discovered genetic linkage.

Educated at the University of Cambridge, Punnett began his professional research with structural studies of marine worms. Later his interest turned to genetics, and, while a demonstrator in zoology at Cambridge (1902–05), he joined a genetic study group under Bateson. Through his contact with Bateson, Punnett came to support the theories of Gregor Mendel, the founder of modern genetics. Subsequently, he wrote Mendelism (1905), the first textbook on the subject.

Using poultry and sweet peas, Punnett and Bateson discovered some of the fundamental processes of Mendelian genetics, including linkage, sex determination, sex linkage, and the first example of autosomal (nonsexual chromosome) linkage. In 1910 Bateson and Punnett founded the Journal of Genetics, which they jointly edited until Bateson's death (1926). In 1912 Punnett became a fellow of the Royal Society of London and was named professor of genetics at Cambridge.

During World War I, when many foods were scarce, Punnett pointed out the value of employing sex-linked plumage-colour factors to distinguish male from female chickens; early identification of the less valuable males was thus made possible. The process, known as autosexing, is treated in his Heredity in Poultry (1923).