Story here. Excerpt:

'“Large public acts of terrorism are very public displays of masculinity, making a statement in the biggest way possible,” says Abby Ferber, a sociologist at the University of Colorado who has studied white supremacist groups and masculinity. In her work, she said, she often encountered a “vulnerability to their sense of masculinity whether it’s their relationship with their father, their culture. And there are a limited number of ways in the culture to show your masculinity.” In the absence of the traditional forms of masculinity — including financial or social power — “you’re more likely to see extreme means. They’re showing that they’re real men, man enough to do something like this.”

Once, Tamerlan’s violence had been on a smaller scale — directed at that woman at the financial head of his table. Friends of Katherine’s told NPR that Tamerlan flew into rages, calling her a slut and a prostitute and throwing things at her. He was arrested in 2009 on a domestic violence charge relating to a different woman. (Dzhokhar seems to have been more like those affable, slightly aimless boys who coast by on charm, with a “permanent stench of marijuana” in his room, according to the Globe.)'