In Terminator Genisys we are led to believe that Skynet created itself. At the start of the movie, Skynet absorbs John Connor and sends him back in time. Then later we see the investors giving John Connor credit for inventing everything in the preceding three years. And then we see young Skynet talking to Sarah Connor about things he did in the future to John Connor. It is as if Skynet exists outside of linear time and essentially creates and recreates itself.
So who created Skynet?