Because his uncles are aunts.
Make the first 21 questions all be the answer C.
Too-whit-to-why
All of if its uncles are aunts!
I don't know but that reminds me of a similar joke my uncle used to tell...
Mom: Well son, your aunt really loves flowers! Son: Mom, what do you love Mom: Richard, stop asking so many questions!
Girl: My Aunt Boy: No it's an elephant. Girl: You obviously haven't met my Aunt