Just to let you.know, this kind of stuff can happen to lots of people. My grandmother was born to a single woman in 1908-ish. It was beyond shocking at the time. She never spoke about who her father was. 2 of her 11 kids heard the name once each in their lives but didn't remember it later. So we have this enormous family and we know nothing about part of it.

My father got Parkinson's (we think due to chemical exposure, not genetic) but while discussing it with his sister, she was like, "We don't have anything like this in our family." I hated to bring it up but I had to say, "We don't know the medical history for one quarter of your background." It stopped her in her tracks because she'd never considered that and she was in her 60s when I said it. I've got one aunt and uncle diagnosed with Sjogrens. They weren't diagnosed until they were in their 60s or 70s. It seems genetic but it's only in "our" family line. None of their cousins families have it.