Alcoholism is definitely hereditary. So is bipolar. But just because you may have the gene doesn't mean it will be activated.
I'm a big fan of Dr. Drew, and he once said something like if you have the alcohol gene plus untreated trauma on top of that, it's likely to develop and addiction.
I haven't drank for 13 years or so but have struggled with other substances. I have no doubt that I have the genetic marker for both BP and alcoholism, as it runs strongly in my family.