sister

This week at school, I had V sitting on the bench outside the infant room to put on her coat & hat (she wouldn't cooperate in her room). I let her stand on the bench outside the window because she wanted "to look at the babies". The conversation went like this:

V (pointing): there's my little sister
me: whaatttt?
V: there is my little sister
me: no it isn't silly. That's G____'s sister (a boy in her class. (He must say that when they walk by the room)
V: where is my sister?

I don't know kid. I was wondering the same thing myself.