Who Knows?

Sons (4 years and 5) Ask mom. Like, my mother, and how we got to see you in the stomach, before birth?
Mom responds:
 - Dad loves Mom, you appeared in the tummy.
Pause, the children go into the next room and came home from work perplexed Pope says, sitting at work, a call from her mother's cell phone, judging by the sounds Jr. tries to take away the older tube, then a senior asks:
 - Dad, Mom and you love?
The Pope, puzzled:
 - Of course I like.
The next question son:
 - Why do we have more children is born?