I don't have any kind of PD, but this was recently replied to and on the main boards, and caught my attention.

I've had a guilt complex for a good portion for a good portion of my life. Major mistakes made in recent years have amplified it to the point of tears and SI trying to cope with it....but even as a kid, I often felt like I needed to hide everything I did, always felt like I was doing something wrong. My mother thinks it's because I never did my homework and barely did any schoolwork, and felt bad about getting good grades without working hard, and the guilt spread elsewhere. I think that's an insultingly simplified explanation, but I don't know where it came from.

So: where does yours come from? What specific things make you think "I'm a bad person"? You don't have to write them here, but see if you can find them. They could tell you something.