There was a reddit user a few years ago that was brought up in an article this year about their theory that The Who's were genocidal and killed the Grinches species years back before the films events. The Grinch was the last of his kind, kept around by the Who's begrudgingly but soon exiled.
What do you think of this? Is it bullshit or something more interesting?
Sounds like an attempt at edge-lord humor.
The two older ladies in this movie who adopted him didn’t seem to have any preconceived prejudices with whatever species he was as a baby.
I sincerely doubt it. Otherwise, the Who's would have discriminated against him far worse than what we saw in the flashback. My theory is that the Grinch is a mutant Who, randomly born amidst all his fellow Who's, and was treated differently by Who's that weren't sure what to make of him.
If he truly was from a throwback species that the Who's had worked hard to destroy, the Who's would have been far more terrified of him than they were in the actual film, and we would have seen a lot more violence and guns involved. They would have done everything they could to destroy him, and yet in the story they did not. In fact, the Who's were only scared of him because of the vicious pranks he'd pulled on them in the past, and the rumors both he and the Who's themselves had spread about him.
It should also be noted that he exiled himself, to Mount Crumpet. Nobody forced him to move there. He chose to go and isolate himself.