Ok, regarding Battlestar Galactica, my theory is that they're ALL CYLONS. All of them. Have been since at least Kobol. All the 'humans' in the Colonies were actually all humanoid Cylons who thought they were human, and had forgotten that they were artificial in nature. And that the original Cylons who populated Kobol came from Earth, in our future, where there was probably a war between the humans and the Cylons, the humans won, and the Cylons fled. Colonized Kobol and forgot that they weren't human. Then, when they colonized the 'Colonies' eventually they recreated Cylons, and eventually, humanoid Cylons.

This has all happened before.

And the 'other 5' Cylons are actually original Cylons from the first cycle.

That's my theory for now.