Agreed. If we weren't already a bit paranoid and prone to paying the hell attention, none of us would have cut the mustard.
As for the egg argument, I feel genetics is an obsolete science. Epigenetics is where it is at. Genetics are merely the documents. Epigentics are the programming that produces such documents.
I also posit that if anyone bothered to take the time and money to do it, one would likely find a direct link between generations and major conflicts pointing more to epigenetic causation rather than specific karyotypes. That is, for instance, my generation's propensity (Gulf War, Central Europe, Africa and the Gulf again) for PTSD is linked to our parent's war (Viet Nam), Their parents wars (Korea and WWII) and their parents (WWI) and so on back through history. The subject sample would be recent veterans with direct descent family members in the preceding conflicts. The control would be recent veterans with no family members involved in previous conflicts.
I personally believe, based on my own previous research, that there is without argument a predisposition to military PTSD, genetic or not.
I guess what I am getting at in laymen's terms is that through epigenetics it takes generations of exposure and overlap to combat stress that results in an individual getting PTSD.