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 but his eyes stay the same. It's sure to be a phony.
The narrator expresses appreciation for their father's genuine nature, highlighting that an authentic smile involves twinkling eyes, which can't be faked. Unlike a superficial mouth-smile, a real smile reflects true emotions, with the eyes revealing sincerity and warmth. The distinction is made clear: a mouth-smile alone can be deceptive.
The narrator warns readers to be cautious of smiles that lack eye engagement, indicating insincerity. This insight underlines the importance of genuine emotions in communication and the ability to discern authenticity from facade in social interactions, emphasizing how true joy radiates through both the mouth and eyes.