From the New York Times:
Mr. Cox, now 32, is the only child of Tricia Nixon Cox and Edward F. Cox. His father, a member of an old New York family, is a lawyer and the chairman of the New York Republican State Committee. His aunt, Julie Nixon Eisenhower, is married to David D. Eisenhower II, a grandson of President Dwight D. Eisenhower.
As a child, Christopher Cox would go to sleep listening to tapes of President Nixon reading books.