I remember watching an episode of the Magic School Bus when I was younger, where they discussed that the food you eat basically colors your skin.
In an example, they demonstrated that if all you ate was carrots, your skin would be orange.
Likewise, if you ate nothing but lettuce, your skin would be green.
However most species need a variety of foods to survive, so the mixture of foods we eat are what give us our complexions.
So maybe the Tau eat only a grey/blue food from their homeworld or something? |