Jan is right (again!) - both my dad and I were "blessed" with AN's. I recently found out he may have actually had them bilaterally, but still trying to get the medical records to find out if this is the case or not. He had advanced Alzheimer's Disease when the possible second one was found, purely by accident, so there would have been no treatment done for it anyway.
I asked my doctors if I should be concerned and they all stated that while it is not considered to be hereditary (except for NF2), there do seem to be some families that just have a predisposition to developing an AN. In my case, I had Radioactive Iodine treatment for an overactive thryoid about a year before my AN most likely started to appear, and studies have shown that certain things, like radiation around your head/neck area can trigger an AN to grow. My guess is that I already had a higher liklihood than others of developing an AN and the radiation just jump started it. Maybe without the radiation, it never would have been there.
When I asked about the possibility of NF2 in my family, my doctors were pretty sure that if it was, my dad's first AN would have appeared sooner - he was nearly 70 at the time, and it was very small and only discovered by accident. They also told me that he would have had other symptoms, which he didn't have. So I guess we can just chalk it up to bad luck, radiation and probably growing up in NJ for my family.
I do watch my kids for anything out of the ordinary, but I'm not going to stress out too much about it. If I see something not right, I know to get it checked out.
Hopefully someday someone will figure out what causes these things so maybe we can do something to prevent them.
Lori