Some time ago, I was visiting a family with small children, and I found the two-year-old middle child with a marker in her hand suspiciously close to some fresh marks on the living room couch. The following conversation ensued:

"Who drew on the couch?"

My older sister.

"Your older sister isn't home."

The baby.

"The baby can't reach this."

The dog.

"You don't have a dog."