Cabot was born in Brookline, Massachusetts. His father was Henry Bromfield Cabot, a lawyer. His mother was Anne Macmaster (Codman) Cabot, daughter of Charles R. Codman.Pg. 21-23 He had five siblings: Henry Bromfield Cabot Jr. (b. 1894), Powell Mason Cabot (b. 1896), Paul Codman Cabot (b. 1898), cofounder of America's first mutual fund and "Harvard's [Endowment] Midas," Anne M. Cabot (b. 1903), and Susan M. Cabot (b. 1907).
