This is a great article on how our brains bias us toward groups. Totally packed with info. Its another twist on Cognitive dissonance in that our brains crave predictability.
It helped me understand again why JW's can't bring themselves to fault the Watchtower (an organization they identify with) while they can point out the exact same problem is other religions. We in fact all do this, for example in a political context when we identify with a political party or specific politician.
In some ways this makes you feel not so smart. We are actually just dumb creatures that go about our life on limited programing looking for predicatble trends that we can repeate over and over again to make ourselves feel better. Ugh where is the inteligent design in that? more research needed I guess.
And on the other hand I think it helps to be more objective with the world. If you can stop for just one moment and catch yourself and notice the bias that your brain is telling you to exhibit because it made you feel better in the past, perhaps you can adjust and actually be a better person.
http://www.npr.org/2012/03/05/147980266/our-brains-betrayed-by-political-inconsistency