In Halo 4, John had his genetic makeup spliced with something called the Genesong, by The Librarian.
She said that the genes were dormant, but that if unlocked, they had many benefits.
One of them was immunity to The Composer, a weapon that encrypts living beings into digital information.
John had his evolution accelerated, but all the Genes need to be unlocked.
Heck, all they really need is someone with the knowledge to unlock them.
I was planning on eventually having them all unlock through each upgrade module.
That's why I was going to have John go through more campaigns.
Not unless he just gets them all unlocked and tries to figure out what they do.:p
If you have any questions, I can answer them.

