There is definitely a significant genetic component, that much is clear. I believe the scientific consensus at the moment is that the genetic component is much larger than the environmental component. I believe bipolar is a physical illness that you can't "cure" through talk therapy the way you can work through and heal from childhood issues.

The way I see it is you have a genetic predisposition towards being bipolar, and it may or may not manifest itself. This is true of many genes; the extent to which they express themselves is based on a myriad of factors. If you're unlucky, the bipolar tendencies may manifest even if you've had a perfectly fine childhood. But I believe a bad childhood increases the chance that it will manifest.

I've often wondered as well whether I would have been this messed up if my childhood had been less ******. At the very least I might have been better able to cope if I had grown up in a secure and loving environment. I've noticed when I'm depressed it amplifies all the other issues and they make it that much worse. Even though I try my best in life and often succeed, it still makes me sad to think about the "lost potential." I wonder how much more I could have done and how I might have made different choices had I had more self-esteem.