In answer to your question about family members: My Grandma (not the one I went to visit today) has panic attacks. I have a couple of aunts on that side who have had problems with it, too. I also have a cousin on that side who has a phobia of vomiting (or seeing other people vomit) that was pretty debilitating for her for a long time and still causes some problems for her. I also have a cousin on that side with some severe PTSD issues - although that's only partly to do with genetics and mostly to do with some horrible things that happened to her as a kid. Several of my cousins, my dad, and 3 of the 5 of us kids in my family pass out at the sight of blood and really freak out about needles (and I mean REALLY freak out). While that might sound like a lot of people in my family with anxiety-related issues, I'm not sure it's all statistically significant, given that my dad is one of 13 kids and I've got over 50 first cousins on that side.
P.S.: We all (with the exception of that one cousin with ptsd and my grandma) had happy childhoods and were brought up in loving households where we didn't really witness any traumatic events or anything. We're also all "easy going," "laid back" people - which is funny since it seems completely at odds with the anxiety we get.