Question

Researchers have found that smiling is something: 1. we learn to do as babies. 2. we learn to do in childhood. 3. that means different things in different countries. 4. that is innate; we don't learn to smile, we just do it.

Answer 1

4 - That it it innate; we don't learn to smile, we just do it.

Smiling is produced when neuronal signals are transmitted to the facial muscles whenever endorphins are produced.