Carlsmith was married to social psychologist Lyn Carlsmith (born Karolyn Gai Kuckenberg, October 7, 1932 – September 1, 2011) from 1963 until his death,[3] and had three children: Christopher, Kimberly, and Kevin (October 17, 1967 – November 19, 2011).[4] He graduated from Stanford University and Harvard University.[5]