 Wainwright was born in New York City, New York, the son of Eleanor Painter (née Sloan) Wainwright (1903–1985) and Loudon Snowden Wainwright (1898–1942).His father, a graduate of the Pawling School and Princeton University, was a senior partner in the insurance firm of Wainwright & Page, Inc.

His paternal grandparents were Stuyvesant Wainwright, a direct descendant of Director-General of New Netherland Peter Stuyvesant, and Caroline Smith (née Snowden) Wainwright.His great-grandfather was politician and diplomat Archibald Loudon Snowden, who served as U.S.