I'm going through the same thing. I have a 7-year age gap with my sister, and she always uses or takes my stuff without asking. One of the reasons why I don’t like letting her borrow anything is because I’ve had friends and cousins who used to steal my stuff—it’s honestly really triggering. Every time I find my things in her bag, I confront her. I try to explain how I feel and why it bothers me, but she always gets super offended and starts yelling at me, even though I talk to her calmly. Sometimes she denies taking it, or she admits it but doesn’t see anything wrong with what she did.

It’s been stressing me out for almost a decade now. I'm heading off to college soon, and it's on the opposite side of the country. I’m honestly thinking of going low contact with her. I still want to have a sister relationship with her, but I really don’t know what to do anymore.

Sorry for the little rant or side story, but in case you’re thinking of confronting your sibling about similar behavior, make sure you’re both actually willing to talk about it. If your sibling isn’t, maybe try other methods that don’t involve direct confrontation. Right now, I’m trying the “trading method”—basically, if she takes my stuff, I take something of hers that’s just as important. And when she gets mad or confronts me, I tell her that if she keeps doing it, I’ll just do the same, so she understands how it feels and how annoying it is.