By Zorianna Kit LOS ANGELES (Reuters) - Breaking out of a famous parent's shadow can be daunting, but Brandon Cronenberg, son of Canadian filmmaker David Cronenberg, is rising to the challenge with his first feature film, the science-fiction "Antiviral." Opening in U.S. movie theatres on Friday, "Antiviral" was written and directed by the 33-year-old Cronenberg and satirizes society's obsession with celebrity with a horrific twist.