One of the most horrifying things about the idea of parenting is raising up a mirror image of your fucked up self.
On the hopeful side: we fuck up our kids in new and interesting ways?
In all seriousness, I'm pretty sure just having the fear of that guarantees you'll do better. It's rational to fear parenthood because of its terrifying responsibility, but you can still be a decent parent even if you yourself were raised by wolves. Therapy -- good therapy -- helps.
At least, I hope it does.