People who were abused or grew up in toxic environments have legitimate rage. Sometimes, as children this rage came out onto others and there is guilt and shame for that. But it is important to remember that as children living in those environments, they were not given the tools to know how to manage their emotions and their models were often violent.
Adults who grew up in such environments have legitimate rage that often still boils under the surface. This is understandable as it has not had a chance to get expressed. Sometimes these folks are irritable and angry in general, the rage is easy to see. Sometimes these folks have strong dissociative barriers to keep themselves unaware of the rage, and they do not seem to get angry about anything, ever. The rage is there but suppressed or contained in another part of self. And sometimes they are able to deny and contain the anger for only so long before they erupt, often over what seems something minor.
All of these were understandable strategies for dealing with the anger and rage when they were young, but are counterproductive to their lives now.
That is why much of the work in therapy is often focused on that anger and rage. I help people to recognize when they are feeling it, teach them how to be able to express it in a healthy fashion in their current life, and to express it in some way towards those who originally caused the rage (often in imaginal or written form).
All humans feel anger and it is an especially strong emotion in trauma survivors. This does not make them bad, wrong or broken. It is a signal that they are not okay with how they were treated, which is legitimate.