Well, in addition to unfortunate mistakes of parenting as well as downright crimes in some cases, they're also the origin of all our genetic code, so in a sense it's almost impossible for them to escape any culpability at all.

I can tell looking at photos of my dad when he was young that something bad was happening to him.. there's a look in his eye that I recognize, one of knowing too much at a very young age, just like I did. Doesn't mean I can ever quite forgive him for passing his pain along to me, but in a sense it does call attention to the fact that the "cause" is not really him but a larger and more terrible cycle of human condition that has probably gone on for many generations. He was the vessel and for me the executor, but not the cause. The best I can do is break the cycle myself, which I have, and probably at considerable cost to myself. It might have been far simpler to continue on in a fog, taking my pain out on yet others, but for me my biggest objective in life has been to ensure that I don't. I'm not a perfect person, but I am a massive improvement on what my parents were.