All for One and Quirk Origin Theory
Okay, so I have some thoughts on 407 and how it recontextualizes the world of BNHA and Quirk history.
According to the latest chapter, not only are AFO and Yoichi twins, but they're also (possibly) the first with Quirks because they're apparently older than the Glowing Baby. Who society (and the readers) have been told since chapter 1, was the first Quirk user.
Over 400 chapters later that no longer appears to be the case. Although we also have to account for unreliable narration messing with the order of past events, and I don’t think we can know for certain if the twins or the Glowing Baby were born first since the twins likely have no actual records of their existences anywhere.
But if the twins truly are older and possibly even part of quirk society's origin, then I also wonder about some of the other things stated in 407 and how it seems like people older than AFO have Quirks.
“Meta abilities… also started to present…. in young people going through puberty.”
Which means that a variety of people were developing meta abilities all around the same time, which led to chaos in society due to inadequate research into the meta ability phenomenon that has been ongoing since the Glowing Baby was born, since researchers “hypothesized that a novel disease was to blame.”
In 407, we see some adult soldiers talking about meta people and coming across a young AFO in the streets, mentioning that they should avoid him because he might be a carrier of the meta ability “disease”. Which means that many believed in the early days that meta abilities spread through some sort of contact with someone who was a carrier.
This line of thought actually makes me believe that people older than AFO (who’s still a young child) have gained meta abilities, as mentioned a couple pages earlier.
We can even see a very young AFO apparently stealing Quirks from people he’s defeated or killed, who look a fair bit older than he does.
Which indicates that a variety of young people all over have suddenly developed powers with the disease line of thought being the most widely spread bit of information to create a wall between those with meta powers and those without.
It’s very likely that the original mutagen could have spread from All for One, or the mutagen could have been something that affected AFO and Yoichi’s mother who then passed along the mutation to the twins, since she was clearly showing some signs of a minor meta ability that AFO stole from her when he was born.
Whatever mutagen it was altered the DNA of multiple people - many of them either born with their meta ability or developing them as minors before and during puberty; which makes me hypothesize that the earliest people with meta abilities, all in the same generation, gained it through some sort of environmental factor and they weren’t all born with altered genetics.
Some sort of mutagen altered their DNA, triggering the appearances of unique powers and appearances, and Ch 407’s narrator makes it seem like Quirks began with All for One and his brother.
I wonder if any of this will be confirmed, or if we’re going to be left to theorize about the origins of Quirks and AFO’s possible role as one of the earliest people with meta abilities.