There are many many many reasons for self harm. Childhood trauma or abuse is only one. Likewise, not every child who has experienced this horror will go on to self harm. It is not something that can be easily defined. I s/h and know others who do. My reasons are personal, however, I have read a lot to try and understand why I do this. I had thought it was an action of troubled teenagers so didn't understand why, in my mid 30's, I had taken to cutting although did previously burn myself as a teenager. I can't say I have a full understanding, I am having to work through it with a psychologist.
Hippy