Its probably because your horny nothing wrong with it but find another girl first and see if you still want to have sex with her after that

Incest is never best dude. And it's illegal and just GROSS. You need to find yourself a girl mate and stop dwelling on the sexual thoughts of your sibling. Take a cold ass shower if you have to curb your horniness. Start masturbating to pictures of naked women other than your sister, you sick freak.

you must be carefull not to let on how you feel,its best to buy a dirty mag wank over that or pay for it,its safer then incest.be carefull

it is illegal, and i think u should get some one else, but it is not the first time i heard it

go and watch some porn, like....right now!! coz wanting to fuck ur sister is not right... at all...in any way!! but cabinet is right, ur a horny teenager and ur sister just happens to be the one u spend a lot of ur time with. u'll get over it

To make it easy on you, DO HER!!!

Do what you want.

You should talk to her about your feeling maybe she being your sister can help you sort this thing out.

Yeah Man! talk to her! let het know how you feel! maybe she feels the same way about you!!

the most natural feeling in the world is when your older sis walks around in her undies is to go and have a J. ARTHUR.

Dude, just type in "sister" in the search box of this website and you will find other people as wierd as you are.