Quoted By:
You can't. It's impossible, you see, siblings have similar genes to each other, and similar genes repel each other. If you ejaculate inside your sister/mother/cousin/aunt/grandma/etc. vagina, she won't get pregnant. The similar genes repel each other. No matter how much you semen you eject, they won't get pregnant.
I tried to impregnate some cousins of mine, since I don't have a sister, and they didn't get pregnant no matter how many times and how much semen.
So don't worry. Your sister won't get pregnant and you both can make love all you want.
