SPINNER IS NOT A FUCKING GECKO MUTANT AND I WILL DIE ON THIS HILL !!! щ（ﾟДﾟщ）
This is either Horikoshi not knowing how to draw reptiles OR an unused plot-point that got scrapped later down the line, especially during "My Villain Academia" season and the "Creature Rejection Clan" episode.
This is the most common shape for gecko fingers, specifically geckos that do not burrow. They have rounded out fingers that are pad-like and full of microscopic hairs that provide a better grip on walls & structures in order to climb.
This is Spinners hand. His digits are not rounded out or padded. His claws are also a bit longer than the typical gecko.
Spinners' hands would be more comparable to a monitor lizard or komodo dragon.
This is another example of how typical anime media portrays komodo dragon hands, as seen in Beastars with the character "Gosha," whose hands and appearance just look like a hyper realistic version of Spinner.
In regards to skeletal/facial structure, they match up as well. For geckos, the majority of their snouts are pointed and get thinner towards the front of their mouth. Even for geckos who have rounded-out snouts, the fingers and colors of those species don't match up with either Spinner nor Gosha.
Young komodo dragons can also, you guessed it, scale walls. Just like geckos, and just like the ability Spinner has. Spinner is only 20, he's still young.
Green komodo dragon. This is Spinner.
So you're probably wondering then why the fuck his quirk is called "gecko."
It's fairly obvious and even directly explained that Horikoshi's intention with how the hero society treats mutants/heteromorphs parallels POC racism in our world. More specifically, racism against black folk.
This was shown directly with how the heteromorphic riot was a reflection of the BLM riots in 2020, as well as the episode where the League of Villains take down the "Creature Rejection Clan."
The word "clan" is literally right there.
A cult-like, masked group that operates to cause harm to mutants based on their mutations.
I don't think that Spinner is a gecko mutant, and I don't think that his quirk would be called "Gecko" either. I think that's just the name society gave his mutation and quirk out of ignorance.
For most people, when someone walks down the street and sees a random person in the context of identification, they default to: "That person is white/black/mexican/mixed."
Not, "Caucasian, Jamaican, Dominican, Puerto Rican, European, Ethiopian, etc."
The hero society saw Spinner at face value, someone with a reptile-like appearance and just defaulted to "lizard" or "gecko."
And that could have been used as an AMAZING plot point that would have led up to the heteromorphic riots & Spinner's backstory in a much better way, instead of jumping right into it all in one episode in season 7 - but as we know, Horikoshi doesn't really do nuance for "backburner" characters. If it isn't Bakugo, Endeavor, or Dabi - the dude doesn't give a fuck.
When Dabi says something along the lines of, "Hold the wheel steady, Lizard." When the LOV is driving a semi-truck to ambush Overhaul after his arrest, Spinner responds with, "It's not Lizard, the name's Spinner!"
That could have so easily been, "I'm not just a lizard!" Or something similar, and opened up a whole different conversation about mixed mutants, somewhat like how Beastars explored that subject.
If that route was explored and Spinner's actual genealogy got explained, the specific species he's mixed with as a mutant, how it effected him as a mutant and the way society treated it, as well as it possibly leading up to his turning point (his assault, getting sprayed with pesticide in public for the way that he looked) - it would have given watchers more of a build-up to the riots.
Not only that, but Spinner could have gotten a sick ass quirk awakening towards the end, not just the extra quirk AFO gave him to break out Kurogiri in the war.
Like how Toga gained the ability to use the quirk of who she transforms into, Dabi having ice at his core, Shigaraki's decay spreading between objects with no point of contact, Twice's death parade, etc.
If the komodo dragon route was actually explored, he would have gotten a venom ability, as komodo dragons have a collection of venom and harmful bacteria that's essentially injected into prey once they bite down through venom glands in their lower jaw.
I hate that this wasn't utilized. I'm sure that Horikoshi just doesn't know how to draw different reptiles and I'm reading too far into it, but I like to give the guy at least the benefit of the doubt and believe that he did have a plan to utilize Spinner more as a character as some point, as well as going into further detail about mutant oppression.
But, in terms of design, Spinner doesn't match a gecko. His "gecko quirk" just "grants the user a reptilian appearance," but he's referred to as a gecko on multiple occasions. He's not a gecko, the reptilian appearance he's granted is modeled after a komodo dragon.
