My little sister is bugging me. I'm wondering whether I should ban my her from reading certain books.
What kind of books is she reading?
She keeps stealing books from my shelves and I want her to stop.
You shouldn't ban someone from doing something positive like reading. You should be encouraging your sister to read more often instead of pushing her away from it, because reading can be a very valuable thing to take into your adulthood and you shouldn't take that away from her.
I'm not a library.
I understand why you'd be annoyed if she's taking your books and not returning them. You should applaud her for being interested in your book and then remind her it's important that she return them to you.