"If genetic modification can be used to create superhumans for example, the governments would surely stop it at all cost because that would be a threat to national security." - Or perhaps they will use it for their own elite soldiers. More likely even.

"Like nuclear weapons for example" - yet many countries have them, they're just not being used. I think same will apply here. Governments will have them, perhaps in secret even for a start but as the tech gets more adopted by mainstream the idea of elite, superhuman soldiers will be more acceptable by the public and it will eventually see broad daylight.

So some changes will be illegal and only allowed for government, rest will be fair game for commercial use.