Where do Babies come from?

Yup, Elijah asked that famous question for the first time today. We were playing with Isaiah and he said, "Mommy, did we get Isaiah at the pet store?" I said, no. and he asked, so where did we get him. I said, "Remember when Mommy's belly got really big and we told you your baby brother was in there. Then Mommy went to the hospital and the doctor helped Isaiah come out." I was crossing my fingers at this point hoping that he wouldn't require any more details just yet. He looked at me for a minute and said "Isaiah just jumped out," motioning from his own belly as though something was bursting from his belly button. I said, "kind of like that." He looked at me again with a look that said, "that's just too freaky and weird to talk about any more," and promptly changed the subject.
A little later, out of the blue he said, "Is a baby going to jump out of Aunt Jess?" She is about to have a baby and he saw her last night. Amazing the things he picks up when we're not even paying attention.
His brain is working all of the time.