Note what he says about violence, incest, rape and homocide. His point is that a great deal of violence, perhaps the majority of violence, occurs between people who know each other. Once again, read Deviant Behavior for an overview, and read Social Deviance for specific insights. Definitions of crime differ too. Violence, for example, is more than the use of physical force.
People label a person violent when that person uses force in ways that they dislike.
What we call violent acts or groups may be more objectively called forceful. Furthermore, the ubiquity of force or violence differs from society to society, situation to situation. In ancient Rome, patrician men could and did kill their wives and children without fear of reprisal. The male head of the house was considered the master of his home and those who lived with him. In modern India, brides have been killed by their husbands and in-laws when their parents did not pay a larger dowry.