Loosely inspired by another thread... have you researched your family history or done one of those Ancestry DNA type things, and what have you dug up?
DH discovered that his grandma's younger brother is in fact her nephew. He was born to her sister when the sister was just 13 years old and DH's grandma was 2 and he was brought up within the family as the baby brother.
DH grandma is 89 now and her sister and nephew/brother are both dead, the sister in her 40's and the nephew very recently.
We've not discussed with anyone what we've found out, I'd love to know if his grandma knows but she's never mentioned it and DH wouldn't dream of asking.
There is no hint within the family that anyone, including the brother/nephew knew, but his birth certificate states his actual birth mother, so I'm assuming he must have found out at some point.
Have you found out anything interesting?