One day, I heard the voices of my stepsister and my father from my father's room... I knew it was bad, but when I looked in, my father had a camera in his hand and my stepsister was giving him a blowjob! I mustered up the courage to ask my stepsister and she smiled and asked me to look again tomorrow, and the next day I looked in fearfully and saw my stepsister having sex with my father. When she realized I was looking, she started to get more and more lewd as she looked at me, which made me get an erection, and when I stayed in my room feeling guilty, my stepsister came and gave me a blowjob, made my dick erect, and then straddled me and inserted it! She even begged me to cum inside her!