Perhaps this is more an explanation than outright help, but am willing to try.
First off, I have never worked for the VA but previously was employed as Veterans Service Officer in Tennessee (am now too disabled myself) - so I do have some familiarity with VA claims.
As to scoliosis, I too went in to the military and served two SEA tours (the second involved several TDY's in-country Vietnam). From my induction physical until my discharge (appx 4.5 years), my scoliosis (which is readily discernable on X-Rays) was not diagnosed. The causal factor of mine was a birth defect - I was born with one leg shorter than the other by an inch or two. The remedy of that day was a weighted boot which I wore when old enough to do so (I don't remember it at all). The remedy worked, but deformed my spine - scoliosis. While in the military, I did not suffer any noticeable pain or other problems and sought no medical treatments accordingly (didn't know I had the condition at the time). I later worked for the Federal Government and in the 80's a contracted doctor took extensive X-Rays during a comprehensive medical exam and there it was.
The VA is right that scoliosis commonly begins in childhood and that a primary factor is genetics. However, as in my case, there are other causal factors as well. According to sources I have researched, scoliosis in adults is commonly a secondary condition due to other factors (e.g. back problems such as herniated discs which cause the spine to deform). Injuries resultant from military service which cause scoliosis are documented.
However, I can tell you that the VA will take the position that, since the condition was not treated by military doctors during your time in service, there is no linkage between your having scoliosis and military service. The VA guidelines for SC state that the condition must have occured during a period of active service or (in the case of a pre-existing condition) made worse as a result of active service. In both cases, treatment as previously stated is virtually a must to prevail in the claims process. Exceptions to this include cancers, type 2 diabetes, conditions resultant from radiation exposure during 50s bomb tests, etc. which the military will accept as service connected provided the linkage can be determined from medical documentation provided by the claimaint - this medical documentation can be for diagnoses years after discharge.