I've just been talking to someone who was deployed to Afghanistan, and rather hastily by the sounds of it. Echoes of 'nam there.
Yes, basic training does cause PTSD. They call it Common Military Syllabus (Recruit) or CMS(R) for short when they're being all formal, but it's basic training. They start by taking your identity off you. Your civilian clothes, your first name, the good running shoes that actually fit you and all that? Gone. Your new first name is Private (or Rifleman or Lancer or Sapper or Signaller or Guardsman or whatever the equivalent rank is). Everything you wear will be exactly the same as what everyone else wears. Your stuff in your locker will be arranged in exactly the same way. You will go to bed at the same time and get up at the same time. You cease to be a person and become part of a unit. Think about that term for a moment. "A unit" can be 8 or 27 or 90 men (and women, in some cases). The individuals in it? They're less than a unit, so they don't count as individuals. To reinforce this, your section is inspected, and your section passes or fails block inspection. If your section f___s up, your section doesn't get to go off-base for a long weekend halfway through. That's you and the other 9 men sleeping in the same room as you. When it comes to drill, the whole 40-member Platoon or Troop does it together, get sick of it together, get sore knees together and so on until the whole 40-member Platoon or Troop gets it right. If you (the collective "you") piss off the NCOs, you, collectively, stand out in the cold for an hour in t-shirts and shorts (identical, of course) and then they ask whether anyone's feeling cold, and when someone says "yes" they have all 40 of you doing PT "to warm up." The idea here is to break down your sense of yourself as a person and make you utterly co-dependent, and to instil reflexive obedience. They have no use for rational, decent human beings. They need hashaasheen, assassins, madmen who will risk their lives for the arseholes next to them and kill on command without thinking about it. It helps to keep the recruits short of sleep, so you'll be that. It also helps to fill them with hasheesh, so in your interview process you'll be asked whether you've ever tried drugs, and they prefer it if you say you've had cannabis and didn't much like it, because then they know you're not going to start having hallucinations from the THC they add to your food to make you more easily reprogrammed. At the end of CMS(R), having demonstrated your ability to march, stand still, turn round, handle a weapon, shoot reasonably well, run fast, obey orders, be just like everyone else in your unit, function passably well when you've only had 4 hours of sleep this week and suchlike essential skills, your reward is to show off your uniformity and reflexive obedience with a parade, which your parents and girlfriends can watch. ("Girlfriends: front row, short skirts, no knickers.") You're not supposed to be a person at this stage. You're supposed to be part of the team (and so good at camouflage that your own mother can't pick you out of a line-up). You're also supposed to have no regard for your own physical well-being. Torn tendon? "You've had all weekend to get over that!" If harmful doses of painkillers are what it takes to let you pass the fitness test, you take 'em and pass the test.
So, yes, you do get personality disorders free with your breakfast.
You're right about the baseline, of course. 0.01% to 0.037% or 10% to 37%, either one's a 270% increase, and they don't say who gets the 0.01% or 10% or whatever risk.
Oh, Willie McBride, it was all done in vain.