Little sibling problems?

Ok so my sister is 10 years old. She is really big ( like 5'1). Now heres my question she is the person she is and she still constantly cries for the simplest of reasons and she runs to my parents and crys and tattles when things dont go her way and its annoying as CRAP!!!!! Is she too old for this behavior? Is it some kind of a phase? Please i need answers to this atrocity!!!