My wife and I live in a new house. Just as we were talking about seriously trying to have a baby, my younger sister came to live with us because she was going to school. It would be fine if we were just living together, but my sister seems to have a crush on me and is seducing me with all her might. She jerk me off every day and is thwarting our family plans...! At first I strongly refused, but I gradually became attracted to my sister who is cuter and sexier than my wife... Now the sperm I produce during baby-making sex with my wife is as thin as water! Sorry, wife!