Actually, for scoliosis it does happen, or at least happened to my DH. He was AFROTC and had his DoDMERB. Due to family history he was up front and stated that there was a history (his sister has a metal rod in her back from scoliosis surgery) when he was entering AFROTC. He passed with no need of a waiver, but again it was in his original exam report.
FFWD to his exit exam as a senior. He was going rated, thus he not only needed to pass the DoDMERB commissioning exam, but also the FAA FC1 physical. He was informed that he did not pass. His parents took him to his sisters specialist (world reknown, featured in every med journal) at Sloane Kettering. The doc re-did the xrays of his back, and proved that he did indeed meet the requirements, with no need for a waiver. From what I understand the reason why his xrays with the AF placed him in the DQ is because if you breathe during it, the degree can change. The doc sent a letter with all of the medical exams that his parents paid for to HQ AFROTC. They accepted his report, BUT please understand this doc was a guy that was the DOC back at that time that you would call for advice. He was even in People Magazine for this new surgery to correct scoliosis.
~ JMPO, hard to have the med boards fight the recommendation from a doctor that specializes in this medical arena. IOWS, be like his parents and go to a specialist that only deals with scoliosis. One that does the surgeries.
He flew ejection seat fighters for 21 yrs. and never once needed a waiver.
I am not trying to give you hope. I am trying to say sometimes finding a specialist is the worth the cost. I work in Men's retail. I can tell you that we constantly say for this generation when they are getting fitted for a suit compared to their father, all of them have some form of posture issues. I am not saying they have scoliosis, I am saying that these kids carried 30lb backpacks full of books for yrs, and typically wore it only on one arm, causing posture issues. I yank their shoulders when fitting them and VOILA they are fine. I am not a doc. I am only enforcing why you should take him to a doc. Is it posture or is it a curvature of his spine?
~ I would also say as a parent take him to a specialist regardless of him commissioning. Scoliosis is not something to take lightly. A curvature can impact organs. It can impact their hips, knees, etc. Straightening the spine is important for years to come, especially when they get older.