I was glad my father was an eye-smiler. It meant he never gave me a fake smile, because it's impossible to make your eyes twinkle if you aren't feeling twinkly yourself. A mouth-smile is different. You can fake a mouth-smile any time you want, simply by moving your lips. I've also learned that a real mouth-smile always has an eye-smile to go with it, so watch out, I say, when someone smiles at you with his mouth but the eyes stay the same. It's sure to be bogus.