kids on reproduction

Our friends' dog had a new puppy. 
On the way home from visiting them, Porter and I had this conversation:
Porter: "Is Molly the puppy's mom?"
Mommy: "Yep."
Porter: "Who is the puppy's dad?"
Mommy: "Crosby."
Porter: "Ohhhh, you mean Molly and Crosby got married?"
Mommy: "Right."
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My 6 year old nephew Henry has been watching Life on the Discovery channel.
After watching an episode he asked my pregnant sister,
"So who fertilized your egg?"
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On the way to dance class I had this conversation with my 4 year old niece:
Me: "How come your mom's belly is getting so big?"
Jacie: "Because we're having a baby."
Me: "A baby puppy?"
Jacie: "No, a baby kid!"
Me: "How did it get in there?"
Jacie: (pause) She ate it.