My 2 years old sister can speak only a little !

Hello there Iyy284891086 I would say that she probably can but doesn't need to. Without realising it people talk for her like instead of asking for a dring she might come to someone in the kitchen and maybe pull on their clothing, then the person will turn and say, what's up do you want a drink? Then all she has to do is nod her head. When she starts pre-school you will find she will come home and there will be nothing to stop her. I wouldn't worry, kids do things under their own steam!

Well if you ask me its because of the influences around her. Baby talk is good for babies but when she turns around 2 a good short and simple sentence helps a lot to make her talk.