Thomas Martin Einstein
Albert Einstein had three children, Lieserl Maric (1902–1903?), Hans Albert Einstein (1904–1973), and Eduard "Tete" Einstein (1910–1965), but only Hans Albert is known to have married and had children. Hans Albert's only biological child to survive to adulthood was Bernard Caesar Einstein (1930–2008), who was a physicist and the father of Thomas Martin Einstein.
Mileva Marić
The marriage had been strained since 1912, in the spring of which Einstein became reacquainted with his cousin, Elsa. They began a regular correspondence. Marić, who had never wanted to go to Berlin, became increasingly unhappy in the city. Soon after settling in Berlin, Einstein insisted on harsh terms if she were to remain with him. In 1914, she took the boys back to Zürich, a separation that was to become permanent. Einstein made a legal commitment to send her an annual maintenance of 5600 Reichsmarks in quarterly instalments, just under half of his salary. After the required five years of separation, the couple divorced on February 14, 1919.