Is it because I'm blonde?

A girl came skipping home from school one day.
"Mommy, Mommy," she yelled, "we were counting
today, and all the other kids could only count to
four, but I counted to 10. See? 1, 2, 3, 4, 5, 6, 7,
8, 9, 10!"
"Very good," said her mother.
"Is it because I'm blonde?" the girl said.
"Yes, it's because you're blonde," said the mommy.
The next day the girl came skipping home from
school. "Mommy, Mommy," she yelled, "we were
saying the alphabet today, and all the other kids
could only say it to G, but I said it to N. See?
A, B, C, D, E, F, G, H, I, J, K, L M, N!"
"Very good," said her mother.
"Is it because I'm blonde, Mommy?"
"Yes, it's because you're blonde."
The next day the girl came skipping home from
school. "Mommy, Mommy," she yelled, "we were
in gym class today, and when we showered, all
the other girls had flat chests, but I have these!"
She lifted her tank top to reveal a fully developed
chest.
"Very good," said her embarrassed mother.
"Is it because I'm blonde, mommy?"
"No Honey, it's because you're 19!"