Rare Earth even rarer than thought

Earth is a unique place!  New findings from the study of extrasolar planets show that a high percentage of them have orbits that are the opposite of what we would expect.  In order for them to get that way, they probably have had very violent histories.  Those violent histories would very likely wipe out any smaller, rocky planets that might have resembled Earth.  It is usually assumed that most solar systems form like ours did - but if this assumption is not valid, it means that finding planets like Earth is going to be even more difficult than has been thought.