Is this completely insane?

So my sister has a friend who we have practically adopted and shes kind of like a sister to me. One day when she was at my house her brother knocked on the door and handed me two bags and I was puzzled because I thought she was the only one staying the night but they moved out of the neighborhood and the school is right next door to my house and he had a football game so the plan was for him to go to his game then come back to my house and stay the night. He is really cute and he has a totally ripped body so i'm a nervous wreck around him. We were joking around about ghosts and stuff and then he was scared (ik how weird that sounds but he was) so i told him i would stay downstairs with him. I ended up falling asleep down there but when i woke up and realized the sun was up i got up and went to sleep in my room. Then my mom woke me up and yelled at me for falling asleep down there even though we didnt do anything and didn't plan on it. He barely talked to me. I know he is my "sister's" brother but i think i might be a bit attracted to him. Is this completely insane?|||Nope that is completley normal. You're gonna be attracted to whoever.|||nope i have been engaged and dating my brothers best friend since i was in the 8th grade and here we are 7 years later im almost 21 now alot of relationships happen from siblings friends to be honest good luck hun|||No, not really.