My son was the first to get an AI (type I diabetes) at the age of 10. At that time, I was healthy as a horse (not nearly as big, though..lol). Since then, I've had a sister and a nephew also dx'd with type I diabetes, I have PA and Hashimoto's, my daughter has lupus and my oldest grandson has type I diabetes.
As goolarra said, it's important to keep in mind that the AI's run in the family and because my son was already diabetic, he caught it as soon as his own son began showing symptoms and was able to get treatment immediately.
Being aware of the various AI diseases and their symptoms is the first line defense for your kids.
Our pediatrician keeps an eye on my daughters for me as he knows what ive been through. Every time we go in for a physical, he is mindful of what the symptoms are and does an extra check to make sure none of the ugly symptoms come out :( God help us all if our kids get this zCrap
No kids, but I think that what's really important to know is that AI runs in your family. As you have said, it's not always the same AI. We see families with several different AIs. So, unless you want to test for all of them...
Furthermore, antibodies can be present for years, or even decades, before disease actually develops. Practically speaking, you could be hit by a bus before the antibodies do their dirty work. LOL
Knowing you have a hereditary predisposition to AI is huge information if you start having symptoms. I think I'd let sleeping dogs lie...