The only way to know whether you are a carrier (having one mutated gene) or unaffected (two non-mutated genes) is by genetic testing. There are currently two techniques for this. One is more sensitive and more expensive and looks at the individual bases within regions of your gene, the other looks at the more global region of this gene. To identify what mutations run in a family, they need blood from the affected individual (your brother,) and if possible the biological parents of this individual (to determine which gene came from which parent). Then they would look at your genes and see which genes you inherited from your parents. If you carry no mutated genes, then you are unaffected, if one mutated gene (from either parent) then you are a carrier, if you inherit two mutated genes then like your brother you have CAH. Without the genetic tests, other tests can only distinguish between having CAH or not having it. Twenty years ago, the more specific test didn't exist, the more general test was around but I am not sure was being used as a diagnostic tool. It might have been that they did not find a clear cut answer for you and chose to treat you as a mild case of CAH to avoid life threatening problems. Chances of outgrowing CAH are possible but not probable. A random change in the DNA can change the mutated gene to a functional gene. This would make an affected individual into a carrier, which would manifest itself as always showing an oversuppression and gradually needing less and less of the cortisone/dex or prednisone.