Hunter X wrote:
^That's how I interpreted "Sometimes a Great Notion" as well. That we, the inhabitants of Earth, are Cylons who forgot that we are (and some rediscovered this and rebuilt resurrection).
I don't think so. They seemed to always know they were Cylons and the 13th tribe. They knew about Kobol.
Also, remember that back in season 2 when they were in the holographic chamber, Kara said that earth was where the constellations matached the original flags of the twelve tribes. That's no coincidence. They had to have come from Earth long before the 13th tribe re-settled it as their own.