I want a pet but i dont think my parents will let me get a pet. I dont think they think i am ready?

my little sister got a pet and they r talking about she can take care of a pet. I really think i am ready to own a pet. I dont know how to tell them that though. Im felling they trust my little sis better then me she got a crab and she takes care of it. I really want a hamster for like two months now but i dont know how to tell them. If they let me have a pet what do u think i should get im curious. I like stuff i can hold and play with. Please also let me know how to tell my parents i think i am ready.