So it was always my understanding that my great-grandfather was bipolar and based on my memories of him, I definitely remember what could be classified as serious and chronic depression.

But at Thanksgiving this year my family said he wasn't always like that and that it was something that set in with advanced age. So they were more than a little skeptical of the validity of his being bipolar (and, I suspect the validity of my own diagnosis).

How many of you had family members who were bipolar, or didn't? There is a huge incident of depression on both sides of my family but I don't know how genetic that is.