Masturbating to Stepsister While She is Taking a Shower - Hermione Cringe

I ran into my stepsister in bathroom, She was half naked and so hot. I don't think I'm a horny person but, I had this urge to take a peek on her while she is taking a shower. Somehow my dick got hard and I found myself touching it. She caught me peeking on her and she weren't mad when she saw my dick. Suddenly we started to have a lustful sex with my stepsister