I think I might be in love with my sister, is it okay to bring it up with you?
Are you kidding me? How can you be in love with your sibling? What would this be like?
Be prepared to experience a dramatic joy, you have been warned.
Being in love with a family member is not okay by modern societies standard. You should seek professional help before you act on this. Otherwise you might suffer socially and or it could impact your entire family dynamic.
It will be a Romeo and Juliet relationship.
This notion of your choosing to be in a relationship of sorts with your sibling is beyond the norm, and must not be furthered. Incestuous actions are against the law of nature, things will be so weird in the household and you won't ever be able to come back from that again. Mental help is out there for the taking, so I suggest you gain access to it quick.