I knew all of the guys (including my dad and brother) who were fucking my sister, and she knew that I liked guys too. After dad and my brother fucked her, she'd beeline to my bedroom so that I could suck their cum out of her. She also came to my bedroom after her dates for a good pussy cleaning. And I fucked her too, then made sure she got cleaned out. Mom sis in bed with me several times always said she appreciated me for comforting sis after an aggressive date. Many years later mom asked me if I'd fucked sis when she caught us in bed together all of those times and I said yes! I also told her that I did something else but she needed to let me fuck her to find out what it was. 5 minutes later I was fucking mom and when I finished in her I put my dick in her mouth while I sucked my cum out of her pussy.