Final answer:
Adequate support systems are not a characteristic of violent families; instead, they help prevent violence, whereas factors like alcohol abuse, social isolation, and abuse of power and control contribute to it.
Step-by-step explanation:
The characteristic that is not considered a quality of a violent family is a) Adequate support systems. Violent families often exhibit behaviors such as alcohol abuse, social isolation, and abuse of power and control. These factors are known contributors to domestic violence. Adequate support systems, in contrast, usually help mitigate the risk of violence and aid in the prevention of such family environments.