Adopted sibling doesn't like me ?

Im an adult and my adopted sister is 4 she was adopted at 2 she always seemed to not like me or want to avoid me i didn't live with my parents at the time but im back staying at my parents till i go to college in a couple months its strange i don't know why its been like this since day 1 my mom and older sister says she dosnt hate me but it seems like it i haven't done anything but try and be a good brother what should i do