Gene Simmons is 75 years and 3 month(s) old. He was born in 25 Aug, 1949. Gene Klein, known professionally as Gene Simmons, is an Israeli-American musician, guitarist, singer, writer, producer, actor, and entrepreneur. Gene is also well known by his stage name, 'The Demon.' He lived with his girlfriend for 20 years, stating his relationship with Shannon Tweed as 'Happily unmarried.' He did not want to get married because he considered marriage as an institution. Later in 2011, he got married to her and had two children. His former love affairs include Cher and Diana Ross.