Here's what I've concluded about the genetic aspect of panic disorder:  

I believe there is a genetic predisposition for the anxiety disorders, but all that means is that some people tend to react to stress with anxiety, and others react in other ways (e.g., ulcers).  

I believe that people predisposed to panic disorder are more highly sensitive and reactive than the average.  I see my own high sensitivity as a huge gift, and I wouldn't "trade it in" for anything!