I believe that Vegapunk is the one who provided Sanji’s mother Sora the drug to counteract the effects of Judge’s Lineage Factor experiments on their children. After Vegapunk was absorbed by the World government, one of his Punks is the author the comic strip “Sora, Warrior of the Sea.”

A few of the details that I think point to this being the case:

– Vegapunk worked with Vinsmoke Judge prior to the birth of the Vinsmoke children.

– The comic strip “Sora Warrior of the Sea” has a few very interesting details: The titular hero and the main villain is Sora (who shares the name of Sanji’s mother) as well as Germa, the nation Sanji’s father leads. Vito (aged 36) has been a huge fan of the series since childhood. Given that the raid suit powers all appear in the comic, they were planned well before the children were born.

– Sora the hero fights alongside a giant transforming robot. Our other transforming robot, General Franky, made its debut in Fishman Island after Franky spent two years in Vegapunk’s labs developing weapons based on his schematics. When he debuts General Franky he even says “Vegapunk! Your dream has come true!”

My belief is that one of the Punk-00s (my personal guess is Shaka the Good) is the sympathetic part of Vegapunk, who wrote the Sora series and named it’s titular character after Sora and had them fight the Evil Germa.

Although we now know Vegapunk currently exists in six separate forms, there’s a large part of him that has shown kindness:

– He has a moral compass, as he was furious with Caesar’s lack of morals in his experimentations, eventually dismissing him.

– When Kuma was set to become a full cyborg he granted his last wish and programmed him to protect The Sunny for years until the crew returned.

– He is a beloved figure in his hometown. His main goals were to provide them with heat and worked tirelessly to help them. So much so they were enamored by his kindness.

More than anything, Sora wanted her children to not be emotionless killing machines. She then ingests a drug that is supposed to undo the effects of the alterations to their lineage factors, with Sanji being the only one it worked for.

Who would have the ability to supply such a drug? And furthermore, whose research and various failures are consistently centered around emotions? Vegapunk.

– MADs is the name of the rogue science group Vegapunk previously worked in.

– SAD is a substance that is an application of Vegapunk and Judge’s discoveries.

– That is then use to produce SMILEs, the artificial Devil Fruit of Caesar Clown.

However, it is also the failures of these that are heavily tied to emotions, a concept Vegapunk makes a reference to when we arrive on Egghead. He “can’t control the animal urges” of the Mecha Shark that attacks:

– Failed SMILEs leave the victim unable to do anything but smile and laugh hysterically.

– Sanji is a “failure” for being born with emotions, making him weak in the eyes of his father.

Most importantly, Vegapunk’s own failed fruit that Momo eats also has a glaring weakness that makes it a “failure” Momo transforms unwittingly anytime his negative emotions suddenly spike:

– Chapter 685 when Momo eats the fruit. He is fine after he eats it while he talks to the child. It is only after the Punk Hazard workers come and scare him does he transform.

– Chapter 698 when Momo and Kinemon hear Kaido’s name for the first time. Momo gets scared and transforms suddenly.

– Chapter 723 when Doflamingo goes to pursue the Strawhats it scares Momo and he transforms.

– Chapter 921 when Momo sees Kaido for the first time he transforms from fear.

Vegapunk’s fruit is not a failure because “Momo is pink and not blue” Momo being pink (peach) is just thematic. His name literally means Peaches. He wears them on his kimono. Giolla transforms his head into a peach with her powers in Dressrosa. His pink/peach dragon color is just a trait to match him. Just like how Toki literally has the Toki Toki no Mi or how Orochi literally has the Yamata no Orochi, it’s thematic more than anything.

Vegapunk’s fruit is a failure in the exact same way his mechashark is. The “inability to control the animal urges/instincts” in the case of Momo – its when his instinct of fear takes over and the fruit reacts as a consequence.

With all that being said – here’s some food for thought. If sudden rises in emotions triggers Momo’s power, and Vegapunk gave Sora the drug that gave Sanji his emotions, is this the reason why Sanji’s flames and power scale with his “passion?”

“Does a human burn like that?! I know you Ain’t a Lunarian!!” “I do!! The heat of my passion surpasses the temperature of flame!!”

So yeah, that’s it. I believe that Vegapunk helped develop the drug Sora took to counteract Judge’s experiments prior to their group splitting. One of the Punk-00s is actually the author of the comic series “Sora, Warrior of the Sea” where he named the main character after her, had her fight the Evil Germa and gave her a kickass transforming robot to boot.

Theory by africhic (https://www.reddit.com/user/africhic)