Even kindergartners know this...
“Boys have a penis girls have a vagina.”
I don’t think I even knew those words when I was a kindergartner, but I probably could have told you that “I have a peepee and my sister doesn’t”.
As Mr. Rogers said,
"Some are fancy on the outside Some are fancy on the inside Everybody's fancy Everybody's fine Your body's fancy and so is mine
Boys are boys from the beginning Girls are girls right from the start Everybody's fancy Everybody's fine Your body's fancy and so is mine
Girls grow up to be the mommies Boys grow up to be the daddies Everybody's fancy Everybody's fine Your body's fancy and so is mine
I think you're a special person And I like your ins and outsides Everybody's fancy Everybody's fine Your body's fancy and so is mine