Little Johnny Mommy why has daddy got so few hairs on his head

Little Johnny was eating breakfast one morning and got to thinking about things.

“Mommy, mommy, why has daddy got so few hairs on his head?” he asked his mother.

“He thinks a lot,” replied his mother, pleased with herself for coming up with a good answer to her husband’s baldness.

Or, she was until Johnny thought for a second and asked, “So why do you have so much hair?”