While "Doom" and other violent video games have been blamed for nationally covered school shootings, 2008 research featured by Greater Good Science Center shows that the two are not closely related. Harvard Medical School researchers Cheryl Olson and Lawrence Kutner found that violent video games did not correlate to school shootings. The United States Secret Service and United States Department of Education analyzed 37 incidents of school violence and sought to develop a profile of school shooters; they discovered that the most common traits among shooters were that they were male and had histories of depression and attempted suicide. While many of the killers—like the vast majority of young teenage boys—did play video games, this study did not find a relationship between gameplay and school shootings. In fact, only one-eighth of the shooters showed any special interest in violent video games, far less than the number of shooters who seemed attracted to books and movies with violent content.