Sister Mom
Reddit user sm4k worked with a guy who spent his whole life not realizing that there was something really messed up about his family tree. Then he ordered a replacement birth certificate to get a new passport and that’s when he learned the truth about his biological mom.
“I used to work with a guy in his early 20s that, at the time of the story, was getting ready to go with his family for his first trip out of the country. He was pretty excited and we were getting the play-by-play of all the things—where they were staying, what they were going to do, how he was preparing…
Specifically, he needed to get a passport, but his birth certificate had been lost. When the replacement one arrived, Mom’s name isn’t the woman he’s called Mom his whole life; it’s his sister. Turns out his “sister” had him super young, and his grandparents basically took him on and raised him as their son and no one ever told him the truth. So Sister was actually Mom, and Mom and Dad were actually Grandpa and Grandma. Real dad is unknown.
He took a few days off work to sort himself out, still went on the trip, still apparently had a blast.”