Trauma does not have to be something monumental to impact the brain.
"Waking the Tiger." by Steven Levine was really helpful for me in this.
I had a pretty good childhood overall, but I had two parents that grew up with active addiction in their own homes. The whole don't talk, don't feel etc was very prevalent.
I had a lot of trauma, mainly from the fact that what I felt, and what I was "told" was going on did not match. Repeated sessions of this imbedded the actions in me.
I went to a trauma workshop not that long ago and got to learn that all of my behaviors were "normal" on the trauma range....it was a huge relief.