There are significant similarities between DuQu and Stuxnet, agreed. However, I don't think that necessarily means they share the same author. Stuxnet has been widely distributed and analysed. There are a lot of smart people/groups in this world and one of them could have decided to use it as a starting point for other purposes. I also agree that it isn't alarmist to believe Stuxnet had a national interest behind it, there has been significant research and evidence to support that, but that is Stuxnet, not DuQu. Again, since DuQu came after Stuxnet it is quite possible that another group is responsible for DuQu that is not related to the original. Although, I do also think that being wary of DuQu until more information is uncovered is wise. I just don't like how the comment about it being created by a nation state is thrown in there casually as if it were already an accepted fact when it is not.