I don't know dude...may be a very advanced form of Genetic Science or Embryo Science or may be Cloning or may be Micro biology. No clue. But if they were able to have a nuclear war during that period they had very advance science and scientifically it has been proven time and again that nothing is impossible. If you were told 20 years ago that Cloning is possible you would have replied they same way?? Would't you?? I used to laugh when Sanjaya used to described the Mahabharat scence to Ghritarastra in his palace but now I believe it is possible if you have live telecast. So dude, it is possible. It is just how you intreprete it.