@boiga:
… so it is possible that nami will meet a parent involved with the revolutionaries or that had been captured by the WG (Vegapunk?)
I agree, having a "scientific genius" like Vegapunk for a parent could help to explain Nami's precocious interest in waves, tides, weather and cartography – but it wouldn't be necessary for both parents to have been navigators for Nami to be a good navigator. (People often travel different paths then that their parents, even though all three possess similar interests and talents. If they didn't, life would be a lot more predictable ... and a lot more boring).
All Nami needed to inherit from her parents was the initial scientific curiosity about the world around her. Nami's own desire to learn (combined with information from the books she stole) would be enough to set her on the right course (pun!) for her current (ha! another one!) course in navigation.
Heredity is only part of the picture ... Environment can also play an important role in how a person develops during childhood. One trait the Mugiwara share is that the environment they grew up was not the environment they were born into (as best we can tell). For example, Luffy was born into a family of devious revolutionaries, but grew up (not on the battlefields of Villa and other war-zones) in a relatively sleepy town in a quiet corner of East Blue, isolated from, and unaware of, the activities of his Hell-raising relatives. So while Luffy's heredity may have given him his relentless drive to achieve his goals, his environment (the people he grew up with and the town he lived in) may have also contributed to his easy-going, carefree attitude -- something that doesn't seem to be part of his father's personality.
For this reason, I'd be more disappointed than amused if Nami turned out to be a carbon copy -- a "mini-me" -- of her Mom or Pop. At most, she was with them for what, maybe three years of her life. That's not enough time to absorb their personalities and habits so completely. Nami's "formative years" (the early childhood years that are said to be the most important in determining how a child will "turn out" later in life) were spent with two people who were not biologically related to her, and who -- I'm assuming -- had very different personalities than her parents did. So while Nami may have received her passion for science from her biological parents, she probably received other important traits -- her resilience, her thrift, her willingness to fight for what she loves and believes in -- from Belle-Mere and from Nojiko.
As boiga put it so well -- if the parent resembles the child too much, then why the heck we are following the story of the child? Why not follow the story of the parent instead, since that story is further along and since the child's version will just be a retread of the parent's version?
Does that make sense?
Thankfully though, from what we've seen of some of the parents of the Mugiwara, the kids are not carbon copies, and not on identical quests. For example, Ysopp and Usopp are very different -- yes, they have some traits in common : their physical appearance, their ability to shoot accurately from a distance, their general good humor, etc ... but they also have enough difference to make them unique, and to make each of their stories interesting. I don't think that knowing more about Ysopp's past will diminish from Usopp's presence, or vice versa. It would though, if both had been more similar than they are.
Sanji and Zoro have no known back story involving blood relatives. Both seem to have left their families to follow their dreams at very young ages. It seems unlikely that their families will come into the story.
I agree with this. One of the reasons why "orphans" (and missing or dead parents) are so common in fairy tales and adventure stories is simply because it's a convenient way for the child to cut all ties with his/her past and go off seeking new adventures. Usopp could not have left Syrup village if his mother was still alive. (His father left it, but, because Usopp felt his father's abandonment first-hand, I don't think Usopp could have done the same, because abandoning the village would be abandoning Mom).
Similarly, if Zoro had parents, it would have been impossible for him to be the head-strong little brat that he was, ("When I grow up I wanna be the strongest swordsman in the word!" … "That's nice dear -- now sit up straight and finish your Wheaties" ...). It's doubtful they would have let him run off, while still a teenager, to make a living killing pirates. They probably also would have objected to him being "adopted" by Sensei after Kuina's death. [yes, I'm aware that Zoro didn't get [I]officially adopted by Sensei, but considering how many of Zoro's memories are framed within the context of the dojo, it seems likely that Zoro was, at the very least, a constant presence, and that he was unofficially "adopted" by Sensei when Sensei gave him Kuina's sword.]
@Moria:
I wouldn't mind seeing Zoro's Dad come in later as a master swordsman who was slaughtered by Mihawk or something. I would like to see Mihawk being Zoro's Dad's equal. It would be a good flashback and great motivation for Zoro to get stronger.
I disagree! – for all the reasons I mentioned above, which can also be summarized like this: if Zoro's dad was the ultimate swordsman who challenged Mihawk and lost, then Zoro is no longer a unique individual with a unique quest. He's reduced to: "DAD -- Version 2.1".
No thanks. I'd like to think Zoro's personality quirks are mostly his own.
However, that's not to say that Zoro's parent's couldn't have been swordsmen (it might be an interesting twist to see Zoro's Mom be the better swords-person of the two…). but I'd be disappointed in Oda if Zoro was simply living out some predetermined destiny foretold a few generations back, because everything that Zoro believes in and stands for now is based on will and self-determination and self-discipline.
I would rather have Buggy Meeting Chopper than Chopper meeting a Reindeer that can't even talk
I doubt that Buggy is Chopper's father, but I love the idea of the two of them bonding over their funky noses. That's a scene I hope we'll see!