Yikes, that’s an awkward sitch. The trick to deal with your self-satisfied sis is to be sensitive to her feelings. People brag for lots of reasons, but it’s likely that your sib might feel a little overshadowed and is dealing with some self-esteem issues. Maybe your achievements at school or triumphs at tennis make her feel like she needs to boast to be noticed. So instead of rolling your eyes, try giving her a nice compliment. After she tells you about perfecting her backstroke AGAIN, a kind “that’s so great!” should give her a sense of validation and acknowledgment.

If you can’t kill the bragging habit with kindness, it’s possible that this behavior is just a reflex for your sis. She might not even realize she’s doing it! Be honest, but kind—you’re doing her a favor by letting her know, but she might not look at it like that. Tell her when you two are alone, and she’s in a decent mood. Lose the ‘tude and save the snarky comments for another time. A sweet, offhand “You’ve told me that story before,” could quiet her, and if she just won’t quit, a simple request to stop might do the trick.

No matter what, you’re stuck with her, so if she can’t lose the arrogant attitude, you need to accept her just the way she is. Good luck, babe!