Everything exists on a continuum. When someone starts to require regid definitions and to try to define "x" is always abuse and "y" is never abuse, etc., someone is going to have experienced something that is an exception to the rigid terms. Sometimes people need to look at their experiences and call it what it is. Sometimes being stuck with a label such as "victim" or "abuser" creates more damage (as when the label begins to define more of the person than the limited area of the person's life and experience where it applies, and it is assumed that the label is permanent and unchangeable).

Is spanking abuse? It depends. Where does it fit on the continuum, how do the parents use it, and how does it affect the child? A light swat to a two-year-old's bum to get their attention might be okay. When spankings occur every time the parents are angry, frustrated, scared, etc., and the parents don't know any other way of interacting with the child, that gets painful to see, and probably will have lasting effects on the child, and most people would call it abuse. The lack of other interactions could be neglect, and might be worse than the spankings. Most of the time spanking will be somewhere between these extremes, and may or may not be abusive.

We are very complex beings, and we are all unique. If a person has a psych condition, then something didn't go the way it was meant to at some point in their life. Quite often some kind of traumatic event has interfered with development in some way. It would be interesting to break it down and see what kinds of events, at what age, what the person's natural resilience or predispositions were, what support was available, etc. But that is such a huge question that it will need to be investigated piece by piece.