Sannah, This is an interesting point...about explaining oneself. I have always done this, more in the past when I was less aware of the causes, but still do it to some extent.
When I was in counseling in my mid 30's with the therapist who pointed out to me that I had been abused (which I had never acknowledged or realized till he said it), he asked me the question, "How do you think this abuse has affected your behavior?" I had to answer I didn't know. His answer: "It makes you anxious." I have come to believe that one way anxiety manifests itself is this need to over-explain one's actions, statements or intentions.
Patty