Bad genes - discovered!

As I mentioned earlier, my daughter and I went on a Civil War treasure hunt for documents in our ancestor's file at National Archives in Washington D.C. Not only did we find family history treasure about my Great Great Grand Uncle Thomas (a huge file of his paperwork circa 1890's), but we also made an interesting discovery. Thomas, whose life and times were so far removed from our own, shared a familiar characteristic with his modern-day relatives: bothersome varicose veins.

It looks like this one particular little health concern is nothing new to Cowhey descendants. Thankfully, not all of us have inherited these bad genes. However, for those who have, they can be quite an annoyance.

My question for The Genetic Genealogist during the Carnival of Genealogy with a genetic twist:

Knowing that you descend from a family with a certain type of ailment (whether it is varicose veins, more serious heart problems, a type of cancer, etc.), what are your options with regard to knowing what the chances are that you have inherited the wrong family gene?

Thomas Cowhey never married and had no children. His brother, William Cowhey, on the other hand, fathered at least twelve children. And they had lots of descendants - a family reunion for this tribe would be a large event. Although I've have not found any of William's medical records, my assumption is that he, too, may have shared the same "bad gene" that his brother did, and therefore many of his descendants are probably suffering from the same ailment or may unknowingly be awaiting its arrival into their lives.