Interesting questions posed by five-year-olds

JJ has a knack for framing acute and frequently challenging questions (this ability is of course unique to her alone and possessed by no other five-year-old ever). They range from the merely sweet:

"Mom, what's the difference between 'blah, blah, blah' and 'tra-la-la-la-la'"?

To the cosmological (and borderline incomprehensible):

"Mom, if the tooth fairy uses the teeth to build her castle or her house or whatever... then the old teeth will go all brown and rotten!"
"Yeah, that's why she's always collecting new ones."
"But.... at the end of the world, I mean when the world breaks into halves... or the world and the moon break into quarters... and there are no people any more... there will still be fairies..."

To the classical:

"Dad, where did the first person come from? 'Cos they didn't have a mummy or a daddy!"

To the painful:

"Why do all the brown people live in ugly houses?"

It's not easy to explain apartheid to a five-year-old.