In my mid-teens I found my Dad clobbering my mother. 

It changed my perspective on all those times throughout my childhood when my mother had given herself a black eye by walking into door frames. I had never seen her walk into a door frame, and yet this is what I was told, and knew no more then than to somehow believe it.

There'll be people who knew what was going on, and also people who didn't think they knew what was going on until they allow themselves to think the unthinkable.