5-year-old rationale:

Taliesin eats his carrots heartily, because, despite our efforts to explain to him that our families are all genetically predisposed to needing glasses, he believes that "carrots are good for eyes", and maybe they will keep him out of glasses. And we can't really argue with the first point, and, after all, we're glad he enjoys them!

At dinner this evening, Tal exclaimed out of the blue: "There's a bunny in the world who doesn't like carrots!"
Mama: "Really?"
Tal, smiling: "But he's in a book."
Mama: "Well I'm sure there must be SOME real bunny who doesn't like carrots..."
Tal: "Where!?"
Mama: "Maybe in a country where rabbits live but carrots don't grow."
Tal: "What country is that?"
Mama: "Um. Maybe someplace in Africa. I don't know, but I'm pretty sure there are rabbits in some of the grasslands, but maybe no carrots. Other root vegetables, maybe. I don't know."
Tal: "Oh, yeah. Right."

...later, while Pappa was brushing his teeth, Mama overheard:

Tal: "Pappa? I think all the people in Africa are blind."
Pappa: "Huh?"
Tal: "They're blind because they don't have any carrots to eat!"
Pappa: "Well, uh... I see. That's interesting, but maybe not really true..."

...etc...