Minor suggestion:

Ok, so these two genes do exactly the same thing...

The only difference being their names, what aspect of the pet's genetics it is affecting and what species of beast.

Now, I was battling with my dragon with Boiling Blood when I read this: "You go berserk!"

Can this please be reworded to "Your blood starts to boil!" Or "Boiling Blood kicks in!" Or something that is less confusing and doesn't mention anything to do with "berserk"?

(I'm not putting this in the text issues forum because I feel like Berserk might have been used for Boiling Blood happening in multiple places, which would mean it would have to be changed in multiple places.)

Basically both of these genes activate the same ability which is Berserker, that's why they have the same text in battle and provide the same ability for the Tactic Map.

As for the backstory, the difference between these genes is only in the way how they activate this physiological state. In case of Brains gene the activation lays on the neuroregulation while in case of Internal organs the trigger is hormones that act through humoral regulation (meaning they are transported with blood), but the result is still the same. The ancient Dragons even had the same trigger mechanism with feline creatures, but later it was fully replaced with the humoral activation which turned out to be safer for the reptilian physiology.