"The study compared SF Soldiers against other soldiers in SERE, including Rangers, aviators, etc."
I didn't read that part in the article and I don't know where this information is coming from. Not to mention the article itself was pretty vague but really interesting.
However, assuming that statement is correct and that is the "control group", the results would definitely indicate that training is the source of the neurological response.
If this was an inherited trait or a genetic difference the idea that all of the people who exhibit it would find their way to the SF's instead of the Ranger regiment or an aviator slot is highly unlikely, actually more like preposterous. Although I am not about to attempt to compare these jobs last time I checked Rangers and Pilots on average are pretty high speed. The likelyhood of all these genetically similar people winding up among any one particular group is very unlikely.
I agree with you 18Dave. They should have a better experiment. Also they should look at other factors like you mentioned age, experience, etc... The egg came first. Ever noticed how much the egg looks like a cell.
http://www.howstuffworks.com/question85.htm
Chickens evolved from non-chickens through small changes caused by the mixing of male and female DNA or by mutations to the DNA that produced the zygote. These changes and mutations only have an effect at the point where a new zygote is created. That is, two non-chickens mated and the DNA in their new zygote contained the mutation(s) that produced the first true chicken. That one zygote cell divided to produce the first true chicken.
Prior to that first true chicken zygote, there were only non-chickens. The zygote cell is the only place where DNA mutations could produce a new animal, and the zygote cell is housed in the chicken's egg. So, the egg must have come first.