David Duchovny has checked himself into rehab for sex addiction. The 48-year-old X-Files star, who plays a sex-obsessed writer on Californication, has a long-standing problem with Internet pornography, said, but has not cheated on his wife, actress  Téa Leoni. “It’s news to me,” said Duchovny’s friend Matt Dearborn. “He didn’t seem any more or less horny than anyone I worked with.”