Genetics determine thc % not the environment. The only advantage to outdoor growing is larger plants.
As genetics may determine thc % does not mean that it will be what it says. It is about the envionment. If temps are too high or too humid they may not produce to that potential thc percentile. As you will get much bigger plants outdoors doesn't mean you'll get that 23% thc unless conditions are at its best during the whole year. Just the same for indoors. If your room temps are too high then it won't come out to it's potential thc levels as if it were optimal w/ perfect temps and enough lighting, ph, etc.