Something something I think the Vinsmokes should have adverse effects to show how their brains and genes were literally rewired to the point where they probably classify as a subspecies of human. Certain parts of their brains were suppressed and altered, their whole nervous systems probably altered too. Literal genome manipulation was done. And let's not forget about the drug Sora consumed while pregnant. If it made her sick, who's to say it didn't cause irreversible effects on the babies, too? God I bet Chopper has a field day when examining Sanji, especially after his mutations start to take effect. His tests might come back inconclusive or with unusual results in general. Any brain CT could look completely fucked, abnormal and concerning, when actually for him it's healthy and as it should be. The siblings are literally a doctor's/researcher's dream patient.
And idk how to fit this into the post exactly but Ichiji having this morbid obsession with the human brain to the point it HAS to be a sign of a mental disorder that cant be properly diagnosed due to the suppressed emotions and Yonji having pica due to some alterations done to his brain or perhaps a trauma response but because his emotions/ect. we're fucked with there's really no way to properly know being two hcs of mine. That also includes how Sanji responds to anything even vaguely explicit; his libido, and his brother's for that matter, all being altered in some way, from extreme levels (Sanji) to minor (Ichiji).












