Personally, I thought the mystery in that regard was one of the show's strengths, and among its positive contributions to the sci-fi genre. And here I go getting sucked into discussing the merits of the show!
Battlestar Galactica is an inherently conservative show, it is hard to get away from that fact. It is conservative in many ways, it is conservative in its technological assumptions, it is conservative in its philosophy on mankind, on war, and on religion. Most sci fi shows lean towards the athiest liberal audience, BSG goes the other way, sort of in the C.S. Lewis tradition.