Well, that’s because, at some point, they were all holding hands in one big hacker Petri dish. The reverse engineering gurus over at Kaspersky Lab have been traveling back in time to when the viruses were wee tots and have figured out that all three share bits of code. From the BBC:

Alexander Gostev, chief security expert at the Russian-based security company added: “The new findings that reveal how the teams shared source code of at least one module in the early stages of development prove that the groups co-operated at least once.

The viruses have been popping up on Iranian computers starting back in 2010, when Stuxnet crippled one of that country’s nuclear facilities, and they were probably lurking around much earlier. There has been wide speculation that the highly-sophisticated code was hatched jointly by U.S. and Israeli government eggheads. This new code-sharing discovery can only fuel the fire that the two governments have been working in tandem, but both have denied allegations of launching any viruses.