Ronald Reagan at 100

The Reagan family poses for a portrait in 1966 during Ronald Reagan's successful California gubernatorial campaign. The Reagans' son, Ron, pictured above as a young boy, has written a memoir, "My Father at 100" to mark the 100th anniversary of his father's birth. Watch an interview with Ron Reagan on "20/20" Friday at 10 p.m. ET. CLICK HERE to read an excerpt of the book. (Courtesy Ronald Reagan Family)