- -gen comb. form technically meaning "something produced," but mainly, in modern use, "thing that produces or causes," from Fr. -gène (18c.), from Gk. -genes "born of, produced by," related to genos "birth" (see GENUS (Cf. genus)). Originally in late 18th century chemistry and probably reflecting misunderstanding of -genes, as though it meant "that which produces."
Etymology dictionary. 2014.