I am one of those people who seldom smile when photographed. I wonder if it's related to my personal beliefs. I don't believe in perfection of pictures. When I see a great photo, the first thing that comes to my mind, "What's beneath that smile? Is the person as happy as he or she portrays?"
There must be stories beneath each picture. Be it dark or bright as day.
An example of this, I use to wonder who took a particular picture. If he is not a photographer or at least into photography, why is he taking the picture? Don't they think that he or she might want to be in that picture too? Is he/she isolated, a pushover or something? Or the others think he/she is too ugly to be in that picture? That's not so good, right?
But in the simplest words, regardless of my arguments, I am not photogenic. Hahahah!