There's a history of many things in my family...cancer, depression, addiction, etc.
My husband's family has addictive personalities and health problems as well, potentially more dangerous than the addiciton or depression I may cause through genes.
I have faith that no matter what my baby is born with, it's going to be all right in the end. If the kid has bipolar, sad, but we'll support him/her in every conceivable way. If the kid is born with physical problems, God willing, we're going to hold their hand and teach them to be strong.
I think that if you are capable to look past it, if you are willing to try everything knowing the risks, then if it occurs, it should have been. Having the factors for things often causes them, but it doesn't always. I'd honestly be pressed to find an entire family who doesn't have some history of mental health issues...of any kind. You can probably find every one in the DSM in my family!