I failed the "Where do babies come from?" question, but only because my son is a biology nerd.

Last night Charlie, my four year-old son, asked me how a daddy puts a baby in a mommy. 

Fear not. I was ready. 

"When a mommy and a daddy love each other," I said, "a baby is born inside a Mommy."

Charlie stared at me for a second, shook his head, and said, "I don't think that's right, Daddy. That's not how it happens. That doesn't make sense. Maybe the doctor puts the baby inside the mommy."

He was genuinely disgusted with my answer.

Then he asked me how a baby could survive in a woman's tummy "with all those gastric juices," which led to a discussion of the womb, which I quickly discovered I was ill equipped to have.  

The boy is obsessed with the human body and might know more than me before long.