Born and raised in California, Zen is the son of well-known actress Nan Martin and her second husband, architect Harry Gesner. After high school Zen studied with South Coast Repertory Theatre in Orange County, California, and the London Academy of Music and Dramatic Art (LAMDA) in London, England. One of his first film roles was in Dumb & Dumber, written and directed by brothers Bobby and Peter Farrelly, and in 1995, he wed their sister, Cynthia Farrelly, a lawyer. A number of movies followed, and from 1996 to 1998, Zen and Cynthia lived part-time in Capetown, South Africa, where they had their first son, Finn Harry Gesner, on July 24, 1997. They moved back to the U.S. when the series concluded, and had two more sons -- Rory Farrelly Gesner, born October 9, 2000, and Tuck John Gesner, born July 11, 2003.