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.