One of the hardest things to teach young children is the practice of not staring at something that's unusual, especially as it relates to other people.
Kids are naturally open and curious, soaking up new information, so when they see a person that's not exactly like them, they treat it as an educational opportunity.
As it turns out, staring at facial deformities is the brain's way of determining if being in close proximity to that person is safe or unsafe.
When the pieces you supply match nothing in the gallery of known facial expressions, when you encounter a person whose nose, mouth or eyes are distorted in a way you have never encountered before, you instinctively lock on. Your gaze remains riveted, and your brain stays tuned for further information. So looking is completely normal.
Now if we could just teach them not to comment on what they see in a voice that can be heard for miles.
Why it's hard not to stare at facial deformities, via BoingBoing