By the time Matthias was in seventh grade, he felt he’d better belong to some group, lest he be alone and vulnerable. The punks and anarchists were identifiable by their tattoos and hairstyles and music. But it was the skinheads who captured his imagination. They had great parties, and everyone seemed afraid of them. “They really represented what it meant to be a strong man,” he said.   What draws young men into violent extremist groups? What are the...
