From reddit: I just found out I've been having sex and in a relationship (engaged) with my uncle. We both didn't know.
"It's a big one! Where to start. Also I'm on a phone do please bare with me.
So I'm 20, my uncle "dan" is 23. My birth father died before I was born. He was in a bad car crash. My mum and him where young. 17 in fact and she and him were not together long. She had only met his mum. Absence dad etc and obviously dan was only toddler.
So skip forward..."