system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] What is the Hulk?

I understand he's a personality, one of many. However that doesn't explain his physical appearance. Is he a mutated human? A monster of another species? Is he his own species? What is his race called if he's not human, and how did he come to inhabit Banner's body and mind?
gpt
He is a Mutate. 

It's a separate, undetectable gene from a mutant gene. With mutants, the mutation is triggered typically by puberty. With a mutate, an event triggers the change - be it a radiation event in space, a genetically modified spider.... or getting hit by a gamma bomb.