In the core of Genesys, we only have one knowledge skill. Appropriately enough, we call it Knowledge. Knowledge is a very broad skill that represents your character's grasp of anything there is to know, from physics and biology, to quantum mechanics, to art history and philosophy.

Not every character is going to be a math prodigy and a philosopher and a historian all in one, so it's up to you to determine what kind of knowledge your character specializes in. Also, you should note that just because a character doesn't have ranks in Knowledge doesn't mean they are completely ignorant. We assume everyone has some basic knowledge of how the world works and, depending on the setting, probably has the equivalent of a primary school education. A couple of ranks in Knowledge may represent some sort of secondary school or apprenticeship, while more ranks may represent the equivalent of a college education. Five ranks may represent being a true prodigy in a specific field.