Confession time; I lost my virginity to my stepsister.
That's kind of serious. Did she come on to you first?
No, honestly, she was the only person who agreed to do it with me.
While I don't think its inherently wrong that you had sex with your stepsister, society does consider it a taboo as you are basically living together as a family unit. That being said you aren't related by blood and it isn't illegal, it's just frowned upon.
I don't care about society. I just wanted to get rid of my virginity.
It's not just about society. People who are related to you can have power and influence over you even if you don't realize it, and vice versa. It's not psychologically safe to engage in relationships like that with power imbalances or possible grooming.