Can I turn a brother/sister relationship into a romantic one?

Okay boys I need some major help on this one, and I want to make the right decision. There's this guy *sigh, we have a brother and sister relationship, like a legit brother/sister relationship without technically being related. Our moms are best friends, he's friends with my brothers, he calls my dad the father he never had. About me and him we've known each other ever since I can remember, we were so close growing up. He's a bit older than me like 4 years, so he guided me through high school (his last year) my first year. We are literally like only blood seperated. He calls me little sis, we talk on the phone about my education e.t.c. He tells me he wants me to suceed in life blah blah, he asks me about my family, I ask him about school yada yada, he just finished med school and he's doing his interning and he's about to get his white coat. Anyways looooong story short... I have sort of developed feelings... ahhh... I don't know where they came from, like before when other girls would talk about him I'd be like ew he's like my brother but now it bothers me! In short my question is a) do I have a chance in hell? b) am I in danger of ruining our PG relationship c) is there anything I can do without being outright about abrupt about it d) will I creep him out? How do I go about this!? I DO NOT want to ruin this relationship, guys do any of you have this type of relationship and have you ever thought about the girl romantically, like even if its a best friend? I might have to add that he has never done anything or said anything to make me think he likes him, it is extremely platonic! Either that or I am C.L.U.E.L.E.S.S. and I have a question for girls too have you ever had this type of relationship and successfully turned it romantic? Everyone should I put the moves on him :O ahh I don't know what to do, I am now afraid of being alone with him and I'm afraid this feelings are TOTALLY onesided... Helpp and thanks for reading my novel :P
Can I turn a brother/sister relationship into a romantic one?
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