There is ample food for thought in this article on causes and potential preventive measures for your violence. ... The percent of guns obtained from home or a relative was 68% in the Secret Service study, 67% in the Newman et al. (2004) study, and 53% in the CDC study.
Am Psychol. 2016 Jan;71(1):17-39. doi: 10.1037/a0039687.
Bushman BJ1, Newman K2, Calvert SL3, Downey G4, Dredze M 5, Gottfredson M6, Jablonski NG7, Masten AS8, Morrill C9, Neill DB10, Romer D11, Webster DW12.Author information
School shootings tear the fabric of society. In the wake of a school shooting, parents, pediatricians, policymakers, politicians, and the public search for "the" cause of the shooting. But there is no single cause. The causes of school shootings are extremely complex. After the Sandy Hook Elementary School rampage shooting in Newtown, Connecticut, we wrote a report for the National Science Foundation on what is known and not known about youth violence. This article summarizes and updates that report. After distinguishing violent behavior from aggressive behavior, we describe the prevalence of gun violence in the United States and age-related risks for violence. We delineate important differences between violence in the context of rare rampage school shootings, and much more common urban street violence. Acts of violence are influenced by multiple factors, often acting together. We summarize evidence on some major risk factors and protective factors for youth violence, highlighting individual and contextual factors, which often interact. We consider new quantitative "data mining" procedures that can be used to predict youth violence perpetrated by groups and individuals, recognizing critical issues of privacy and ethical concerns that arise in the prediction of violence. We also discuss implications of the current evidence for reducing youth violence, and we offer suggestions for future research. We conclude by arguing that the prevention of youth violence should be a national priority. (PsycINFO Database Record.