I'm not a psychiatrist, but there seems to be a 75-80% genetic correlation to bipolar disorder. However, that doesn't mean that if one or both of your parents have/had bipolar disorder you have a 75-80% chance of having bipolar disorder; it means that you have a 75-80% chance of having a trigger to bipolar disorder.

Again, I'm not a professional, so I might be 100% incorrect.