Would it be weird to have sexual relations with a longtime childhood friend? ?

I have a family friend who ive been friends with forever. We are both 23 now and we still hangout and have great times together. We are both single at the moment and recently I find her to be quite stunningly attractive! Shes told me im attractive too and enjoys my company but I cant see us being boyfriend and girl friend or anything. But sex has crossed my mind! Sometimes we get close/ watching a movie and I can feel a spark! Like I could lean over and kiss her and start something. Ive also touched her legs and sholders and what not and shes receptive to my touch. She doesnt freak out or anything. But im not sure if she wants that are not! We are sort of like brother and sister almost but yet our hormones are raging! I dont weather to try anything or not!