I have 4 kids

I thought I had 3, F1-1, F1-2, and F1-3. But I stand corrected. This morning I was reading "Two Peas in a Pod" by Annegert Fuchshuber with F1-3. It's a cute book about animals that have 2, 3, or more babies. The beetle even had 51, and didn't even think it was too much. I then asked F1-3 how many children I had. She answered right away: "4."

Huh? Me: "How did you get 4, I thought I had 3 kids?"
F1-3: "No, you have me, F1-2, F1-1, and daddy."
Me: "But daddy is not my child, he's a grown-up."
F1-3: "But you call him 'baby'."
Me: "Oh, ok."