Koufax was born Sanford Braun on December 30, 1935 to Evelyn (née Lichtenstein) and Jack Braun in Borough Park, Brooklyn. His parents divorced when he was three years old. The son of a single working parent, he spent most of his childhood with his maternal grandparents. Evelyn eventually remarried when was her son was nine years old, to Irving Koufax, whose name Sandy took. Koufax also had a stepsister, Edie, Irving's daughter from a previous marriage.
