Kay Winthrop was born in Ipswich, Massachusetts, a direct descendant of John Winthrop: the descendant line is Gov. John Winthrop, Gov. John Winthrop II, Magistrate Wait Still Winthrop, John F. R. S Winthrop, John Still Winthrop, Francis Bayard Winthrop, Thomas Charles Winthrop, Robert Winthrop, Frederic Bayard Winthrop. Kay Winthrop's parents were Frederic Bayard Winthrop (November 15, 1868 -- May 6, 1932) and Sarah Barroll Thayer (born February 18, 1885). She had five siblings:
Kay Winthrop
Sarah Barroll Thayer