is a senior correspondent for Vox, where she covers American family life, work, and education. Previously, she was an editor and writer at the New York Times. She is also the author of three novels, including the New York Times bestseller Outlawed. We don’t know much yet about the shooter who killed one man and wounded two others in an apparent assassination attempt on Donald Trump on Saturday. We do know that he was 20 years old, and male. Those two facts — and his role in Saturday’s shocking crimes — put him in a small but frightening group: He’s...