Well this is complicated. My sister and I are having sex since we were teenagers and it was at that time we got new neighbors and she became best frined of their daughter. Time passed and I started dating out neighbor's daughter and still having sex with my sister when we had the chance. I got married two years ago and at that time my sister and I promised each we would stop having sex but it didn't last.Last year at my birthday, my wife got so drunk that my sister and I had to brought her home and while she was deep sleeping in the bed room, we broke our promise and we fucked in the kitchen. Since then things went just like ii was before. We fuck every time we have a chance.