The short, short version…
Corporate greed, cultural vendettas, monotheistic terrorists, and angsty teens combine to create the Cylons.
That’s right. The destruction of mankind in Battlestar Galactica was brought about by cybernetic whiny teenagers.
Which explains why Cavil on BG was such a manipulative crybaby. Kinda like Lord Voldermort, only more annoying.
The Cylon creed: “You’re not the boss of me!”