When James Alex Fields Jr.’s mug shot was released after he drove his Dodge Challenger through a counterprotest in Charlottesville on Saturday, no one was surprised by what the image revealed: a young, white man with a neo-fascist undercut. “Alt-right” figures like Richard Spencer absorb nearly all the media glare on white nationalism, creating the impression that this is a single-sex movement, and as many have pointed out, the white supremacists who rallied on Saturday were mainly men. When it comes to identifying the perpetrators of racial hatred in this country, it is tempting to comfort ourselves with gender tropes....