Albert's three children were from his relationship with his first wife, Mileva Marić, his daughter Lieserl being born a year before they married.
Albert Einstein's second wife was Elsa Einstein, whose mother Fanny Koch was the sister of Albert's mother, and whose father Rudolf Einstein was the son of Raphael Einstein, a brother of Albert's paternal grandfather. Thus Albert and Elsa were first cousins through their mothers and second cousins through their fathers.^[2]