where do babies come from?

These words just left my son's mouth:

"Mommy I don't have any kids."
"Really? That's interesting. I didn't think you did."
"I don't have any kids but I have a baby in my belly."
"You do? How did you get a baby in your belly?"
"Well, we started off by getting married, and then there was a baby in my belly."
"That's good, you're doing things in the right order."
"Yeah, we got married, and then bam, God popped up and put a baby right in my belly!"

If only I could convey his hilariously serious, proud, and innocent tone of voice.