Liberté, egalité, fraternité?

I had a very enlightening conversation today about the legacy of the French revolution, the three main political foundations of democratic life. Apparently, some lefty theorist says that without those three, the socialism of the 21st Century cannot exist. Don't worry my dears, I am not about to go into the socialism of the 21st Century, whatever the hell that is. What is interesting to me is whether we really can live up to those three standards.
With the right social and legal institutions you can more or less establish the first two. Liberté seems the easiest one: give people freedom of conscience, thought, expression, movement, etc (however, it won't do them much good if they are starving. To be free, first you need to eat). The second one, egalité, is harder, but you can try to apply the concept that everyone is equal under the law and has the same rights and obligations as their fellow citizens. Good luck with that one, if you don't have the money to hire a good lawyer. But we get brownie points for trying, at least on paper.
So far so good.
Yet Fraternité is where we are inevitably going to get stuck, because we seem to be humanly incapable of it. Just take a look around: sectarian murder in Iraq, ethnic cleansing in Darfur, and elsewhere in Africa. People just kill each other for the stupidest pretexts (religion, politics, greed) and it has been like this since day one. A few pages into the Bible, right after the part about Eden, the first two brothers are born and first thing that happens, one kills the other. Not the most auspicious of beginnings.
So Fraternité, which should be as natural to humans as the act of breathing, is the one that needs to be enforced by civilizing laws. People need to be constantly reminded: no, you can't kill your brother, no, you can't steal from your neighbor, no, you cannot abuse your workers, you can't persecute the different, the strong have to help out the weak. No, the world does not revolve around you and screw everybody else.
I have no hope for mankind. Here we are, after thousands of years of wars and discoveries and progress, and we still are killing each other like beasts; worse than beasts, because we have a conscience and they don't.