Found this from Tumblr

Blondes are our record keepers. The great librarians, they collect, analyze, store, and distribute information to the rest of us. They are blonde because they reflect the light of knowledge. Those with Black Hair are our inventors. They investigate, produce, and teach new technologies so that we may thrive in future times. Their hair is black because of their frequent dives into the void of the unknown. Brunettes are our ambassadors. They interact with people, plants, and animals, forging bonds that can protect us when we are threatened. Their hair is brown because of their deep connection to the earth.

And as for redheads.

You don’t want to know the purpose of the Red Heads. But may their hellfire consume our enemies.