How to convince my parents to get a cat?

Just to let you know this is Mollee's 12 year old niece Kelly. One night i went to my friends house she had the cutest little pet it was a cat! After a few hours of playing with her cat i fell in love with cats, so the next day i asked my mom can we have a cat she said no because she hates cats im really mature for my age well more mature than my twin sister Gwen. How can i convince my mom and dad to get a cute little kitty!