June 20:
(1) (1861) English biochemist Sir Frederick Gowland Hopkins was born. He shared the Nobel Prize in Physiology or Medicine in 1929 for discovering vitamins.
(2) (1865) English physician George Redmayne Murray was born. He is credited with pioneering the treatment of endocrine diseases, which include thyroid cancer.
(3) (1875) British geneticist Reginald Punnett was born. He invented the Punnett Square, which is still used today, to predict the possibility of genotypes in the offspring of parents.