Immature Or Just the Way I' Am?

Ok, so in two months I will be twenty and I' am questioning who I' am a great deal. I still like Anime(A lot), RPG Games, Writing short stories and trying to write novels but mostly about the supernatural as well as reading supernatural books i.e Vampires, Immortals, Zombies, Witches et cetera. Anyway, Even though I' am a pretty laid back person, a lot of the things I do and act make me wonder if it's time to grow up or if it's fine because it's just who I' am. This is probably a very controversial debat since those raised in a proper mature setting would say 'Yes, grow up! Your too old' where as others will say "Nah, it's cool, your you". It goes a lot deeper than liking just those things but that's pretty much the gist of it all. Should I just grow up and learn to like new things or am I fine the way I' am?