Do your parents have secrets you found out about?

When I was 15 my mother and I were on a plane to Los Angeles and she was very drunk. During the trip she confessed to me that I had a sister who was the same age as me. Apparently, my father was a rolling stone and got another woman pregnant while my mom was pregnant. Anyone have similar secrets to share. By the way, I met the sister twice when I was 16 but we didn’t like each other. She was angry because my father never acknowledged her but gave me his last name instead so she took her anger out on me.