And resurfacing yet again with Momonosuke, how many times will people have to be told that Momonosuke isn’t Oden before we remember that we’ve been through all of this before. Momonosuke’s entire character arc is that he’s suffering from imposter syndrome because he isn’t living up to the image of his father, due in part to what he feels is undue respect from his retainers. Momonosuke is not even a shadow as powerful as Oden was at literally half his age.
Enter – Luffy who now serves as the grounding that Momonosuke needs in order to force Momonsuke out of his comfort zone and become part of what he believes people expect of him. Luffy treating Momonosuke as nothing but what he is: a kid out of his depths in a position of power because of his father’s legacy, is literally the crux of Momonosuke’s character development. Luffy does not know who Oden was, and doesn’t care – in classic Luffy fashion. He just recognizes that everyone believe Momonosuke is capable of great things, but Momonosuke clearly did not have the will to rise to those expectations until Luffy called him out for it and forced him to.
The same thing Luffy did with Sanji way back at the Baratie. The same trend we’ve seen with so many other characters. The same theme we’ve seen even with characters that definitively don’t have any important lineage, and that we’ve seen with those who fail in spite of their lineage.
Koby and Helmeppo did not rise from their cowardice because of who their fathers were, it was because Garp forced them to, because he recognized that they had the will to become stronger even if they lacked the physical strength at the time. Moria once challenged Kaido, but upon being defeated lost his will to continue and became a shadow of his former self. Yasuie was also the descendant of Ryuma, yet never became an incredible sword master because his will was to protect and encourage people through their hearts and smiles, not through the blade.
The entire point of One Piece is the power of dreams and determination. Lineages are almost inconsequential flavor, if not downright burdens on some characters. The entire story is about taking control of your life and making it your own. That you aren’t your ancestor. Your powers are yours, your fate is your own. Your dreams are what matter, and the people who protected you up to that point did so in order for you to pursue your own life, not to live in a manufactured debt to them, and definitely not because of who you’re related to.
This isn’t even beginning to get into all of the intricacies of “found family” in One Piece, and how most of the characters were adopted and not even raised by actual relatives, and how that is what determined their character. But I digress.
Zoro and Sanji having important ancestors or genetic modification doesn’t really take away from their characters if you’ve actually been paying attention to the themes of characterization in One Piece. They are their own people, with their own ambitions, and their strength is their own.