My Friend s sister hates me?

OK so long story short my friend doesn t go to same school as Me, but her sister does. She always stares at me doesn t say anything just stares each time she sees me in the hallways at school we don t have any classes together thank God, but both of our last hour classrooms are next to each other upstairs at school, when I go upstairs she ll just eyeball me down the whole time for some odd reason then today when I was walking to my class which is upstairs she was walking with her friend and she was talking about me I can tell because her & her friend turned and looked at me, I already know that she doesn t like me she just never told me the reason for it. But should I tell her parents about this?