My cat-__- help? he is annoying, but i love hom?

Well my cat has had a change in attitude latley, he humps things he drags his but all over the floor, and he pounces and jumps on my little brother only. He's pooped on a new blankes that my mom had just bought, and my mom threw it out. My mom has been telling me to give him away! My cat already knows how to poop in his litterbox, wich he does. Why does he do all the things he does like rub his but on my carpet, humps things and always attacks my little brother, what can I do? And what can I do to prevent it? Cuz I want this to stop:(