John Wayne was born Marion Michael Morrison in 1907 and died in 1979 but he was a grandfather and great-grandfather of twins. He was grandfather to Molly and Patrick Munoz-- children of Wayne's daughter, Melinda Wayne Munoz. He was great-grandfather to identical boys, Matthew and Luke-- grandsons to Wayne's daughter, Toni Wayne LaCava, and sons of Toni's daughter, Anita.
(Source: The National Organization Of Mothers Of Twins Club Inc. http://www.nomotc.org/famous2.htm#w )