Albert Einstein married his cousin (Elsa Einstein)

   Elsa Einstein (January 18, 1876 – December 20, 1936) was the second wife of Albert Einstein. Elsa had the surname of Einstein at birth, lost it when she took the name of her first husband Max Löwenthal, and regained it in 1919 when she married her cousin Albert. She began a relationship with her cousin Albert Einstein at Easter 1912,while Albert was still married to his first wife, the physicist Mileva Marić. Einstein's divorce from Maric was final on February 14, 1919, and Elsa married him three and a half months later, on June 2, 1919.