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.
Lewis Einstein
The son of wool magnate David L. Einstein, Lewis Einstein had two sisters: Amy, who married Joel Elias Spingarn, and Florence, who married Sir Charles Waldstein. He graduated from Columbia University in 1898, and earned a master's degree in 1899.