The massacre at Marjory Stoneman Douglas High School in Parkland, Florida, seems to fit what we know about the tragic pattern of mass shootings. Once again, the shooter was white, male, and socially isolated. And in keeping with a number of deadly mass shootings in the past, this one took place in an affluent suburban community not unlike Newtown, Connecticut (where the Sandy Hook Elementary shooting happened), or Columbine, Colorado.

We have data on the kind of person who typically commits a mas…