Of course it's real, I remember reading an article few months ago about its connectivity to the lack of certain nutritions, I know that some people find it so hard to smile, I've heard of a man with a blank face who had been transferred to the hospital after suffering of some cramps in his chest because he laughed, so of course he decided to never do that again.
I'm a smiley face, my husband have fallen in love with me because of my smile, when I see my face in the mirror the first unconscious reaction is that I smile, if my eyes accidentally have a contact with a person my immediate reaction is a little smiling then looking away, although it's not a big smile or else it'd be weird..
And my face is way too expressive..
Edit: try to smile people, seriously, it's better for your health it's illuminating, if you can't then just fake one! it's so awkward for me at least to deal with someone who can't smile and have a dead facial expressions, specially if they keep annoyingly glowering at my face analyzing it , when I sense that I just run away..