When I first heard of this, actually a couple weeks prior to this report, I was thinking exactly the same way. Several years ago, and I am going to refer to FMS because I am more familiar, my doctor told me I had pain amplification and I thought rather she meant "exageration". Actually this is something we can not control--we are very sensitive to pain.
They are referring to genes related to parts of the brain that handle stress. They refer to something else-differences in genetic activity affecting the way they handle accumualted stress over a lifetime. The way I am understanding this now that if it is genetic, we are predisposed and may not be able to avoid this even if we live as stress-free as we know how. Even little children experience stress, probably even from birth. I don't believe we have total control over our ability to process stress. We can avoid some things to reduce stress but even things like physical stress is still stress.
Again, this is just a preliminary study. As time evolves, perhaps other things will be seen as triggers. I would like to express my opinion, here again, about something I believe. Here is one example. My husbands' family has a history of Type I diabetes. Over a lifetime, he was exposed to stresses like serving in the war and coming in contact with toxins. However, the final "trigger" may have been something as simple as the flu virus. (according to his doc)
I did not mean to insult anyone here or insinuate we are just unable to "handle" stress. I defintely include myself here because the same thing is being said about FMS. It is obviously a lot more complex than that, but the possiblity of discovering a "biological basis" may at least be a step in the right direction.