This article--Congo sex abuse claims upheld-- has more on the sex abuse by UN peacekeepers (and one worker) in the Congo. It's not good.
I am tempted to be glib about it because it shows the UN to be a farce in many ways when it comes to any moral authority, but we are talking about the lives of children that have been used up in some pretty thorough ways by these people.
It looks to me like a bit of colonial mindedness that seems to be prevalent with these people. The locals are there for us to use as we see fit for whatever we want to use them for. The UN doesn't encourage it obviously--even they could see the hypocrisy in that--but it seems to foster it some way because it has happened in other places too. (See my post here for instance.)