Gender Confusion

I was in Gracie's bedroom the other day, and she wanted to show me something she had drawn on her chalkboard.  There were two words written there, one in blue (boys) and one in pink (girls).  She told me that the sign was meant to show who could come in her room.  I laughed and said that she was giving permission for everyone to come in if both boys and girls were listed.

Gracie looked at me like I was crazy and told me no.  I tried to explain that everyone is either a boy or a girl which meant that everyone could come in her room.  If she was old enough to understand the art of eye rolling and deep sighs I would have gotten both from her.  She said very patiently, as though I was  slightly mentally inpaired:

"Not Grandpa, because he's a grandpa and not Daddy because he's a Daddy."

 I guess that makes sense because until just recently she thought that the term human meant adults and that children weren't included in that group.  As in, "They weren't humans Mommy, they were kids!"  What will she think of next?