I think my sister is too hot
Why would you think your own sister is hot?
She just is!
Even if she is a pretty girl, you shouldn't feel attracted to your sister. Find a girl who you aren't related too.
Fuck that, who's to say the feeling won't go away spontaneously.
Instead of waiting for those feelings to go away, you should actively try to get rid of them. Nothing good will come of your attraction to your sister.