As a parent, we taught our children to smile, to laugh .. We get worried when the baby starts to cry and we try any means to make the baby happy... so at the very start of child development, a parent brings out the smile, laughter and happinness from a child. The bigger challenge afterwards is to nurture that " happy feeling of a child " towards adulthood.
Not all people's smiles are natural- others are "fake" simply to appease the other person. A true smile radiates in the face, in the eyes of a person........ Have you a seen a person smiling Yet the EYES looks so sad?