Assuming you mean verbally, my sister does the same. Down to the point ,that when she does it, I hate her. She's always been the center of attention in the family '& constantly telling me that I have no friends. Anyways, there's no way you can fully stop your siblings from doing what they're doing, considering that's how siblings are , but there is a way to prevent it and possibly making it happen a lot less often. You need to talk to them about how they're behavior is bothering you '& affect you mentally. If they make a joke about it, then talk to you mom and get some advice and ask for support. To prevent it from happening you need to act a lot less vulnerable '& stand up for yourself. My sister used to always take advantage of me since she was 5 years older than me. As I grew older, '& the more independant I became, - the more defensive I began to be as a person. That means not letting yourself be a easy target. The best you can do is just to buidling a stronger character and stand up for yourself in any situation. Don't let yourself break out. You being such a young age, I would recommend talking to someone that understands you the most in your household. Probably your mom or dad would be the wiser choice.
Good luck , and I hope all goes well ♥