Colgate, a 1922 Yale University graduate, and brother of the Delta Kappa Epsilon fraternity (Phi chapter); was also one of five children of Gilbert Colgate Sr., who was the great-grandson of William Colgate, who founded what is now the Colgate-Palmolive Company. He served as a director of the Colgate company and was chairman of the Colgate-Larsen Aircraft Company. Gil Colgate was concerned about the population explosion and became one of the founders of Planned Parenthood.