how did we get so lumpy?

I don't know how I missed this before, the article over at the NASA Goddard Space Flight Center for science teachers (last edited in 2012). It's entitled The Lumpy Universe and asks the big question: how did the Universe go from so smooth to now very lumpy? Perhaps it is due to the small variations discovered in the cosmic background radiation, first with the COBE satellite and then with the WMAP probe.