Here’s what we know so far: Rob Reiner’s son Nick has been arrested on suspicion of murdering his parents. Nick, 32, cycled in and out of rehab centers, blaming his drug use on the fame surrounding his father and his grandfather, the comedian Carl Reiner. Nick got into a fight with his parents during a holiday party hosted by comedian Conan O’Brien on Saturday night. Family friends told The Times that Nick had been living in a guesthouse on his parents’ property and that his mother had become increasingly concerned about his mental health in recent weeks. The medical examiner...