From a biological point of view, this is very unlikely. Mutations as drastic as the addition of a new organ (meridian/dantian) could usually only occur naturally after several generations. In other words, to be natural, He Gang would have to spend a lifetime in this Danger Zone, only then could his grandchildren, great-grandchildren or who knows how many generations later be born with meridians.All of this talk about He gang and how he has Qi got me thinking...what if the answer was more simple than it seem? This is only a speculation but what if he got them naturally? It always struck me as odd that He gang was said "to have delayed his come back to the sect", to leave the mountain there are only 2 ways, 1 through missions and 2 by order of an elder or a personal problem like the Wu mission, yet in 3 years He gang never came back to the sect meaning it is more of a personal matter than a mission which lead to an answer what if he got Qi and meridians through a danger zone? Tang wei said that meridians are a "natural mutation" in Qi rich worlds and Danger zones are fragmented worlds, what if He gang went into a Danger zone that is rich with Qi and through the 2,5-3 years he spent there he "mutated" and got meridians?
(I'm not an expert by any means, I just had a certain interest in the subject a few years ago, so I could be talking nonsense)