I've blocked out my childhood?

When I try to think about it I don't really remember much about my childhood. I didn't have a great childhood. I think I had depression. My sister also told me she was terrified of me when I was a kid. She said I used to chase her with a hammer and I threw a pair of scissors at her and I chased her with a knife once. I don't remember it that well though. I don't get why I would have blocked out my childhood. It's all kind of a blur..