Hi Jen,
I asked my neuro about the genetic predisposition. In fact that is exactly what I called it. He said "yes", but a qualified "yes." Briefly, he said if one side has it, the other side is more likely to get it for a couple of reasons. First, the cubital tunnel area is probably the same. Second, the underlying activities, if any, that agrevated the first will probably be there for the second, too. That seems to fit my case.
I started doing more preventative stuff for my right arm much sooner than for the left. Time will tell how much good that will do. So far, it seems to be regressing more slowly than the left, but still too fast.
BTW, I'm going to go thump my kid on the elbow and blame it on you
