[Meta] Heredity in Naruto

[ishime]

Warnings:
I suck at arguing (except in the "yelling at each other's head" sense), so I guess I kinda suck at meta. Therefore, this one will be a series of lists of personal opinions and criticism.
Also, it contains mentions of - and arguments sort of in favor of - incest and selective human breeding in Naruto.
This is for hungrytiger11 , who asked for Naruto meta for Christmas, and doesn't care how late I am ~ ♥

So I have a few issues with the concepts of hiden jutsu and kekkei genkai, and instead of just ranting against it in my weekly Naruto rants, I've tried to organize my thoughts into something more or less meta-like.

Canon facts:
              1. The use of chakra called ninjutsu was either created or taught to the ninja masses by a priest, the Sage of the Six Paths, and every ninja is a descendant either of his children or his students (edit: I meant ninjutsu was transmitted either from a parent to their offspring or from a former student to the next generation of students).
              2. Ninjutsu is using chakra to perform jutsus. To perform a jutsu, you have to mix the chakra (mix the mental and physical energies), and then (possibly) give the chakra form and/or nature.
              3. Another characteristic of chakra was mentioned (the ying and yang, mentioned by Kakashi).
              4. Ninjas have elemental affinities: not every ninja can give one particular nature to their chakra; each ninja has affinities for some nature (determined by the test of the leaf, strangely similar to the one used in HunterxHunter - copying Togashi, much, Kishi?).
              5. Some ninjas using non-elemental skills (Shikamaru and Tayuya) have been said to create a peculiar type of chakra, by mixing the spiritual and physical energies in peculiar proportions (Shikamaru analyzing Tayuya's attack, and comparing it to his clan's jutsus, which are officially classed as non-hereditary).
              6. There are three types of jutsus (ninja skills): common jutsus (any ninja, provided he has an affinity for the skill's element, etc, can use it), hiden jutsus (jutsus any ninja with the proper affinities could use, but which are kept secret by a clan) and kekkei genkai (hereditary jutsus, which can only be used by the ninjas from the related bloodline).

... And I might have forgotten something important here. I don't really get the chakra system's logic (I find it rather dumb and frustrating, actually).

Canon stuff I find illogical and frustrating:
              * skills are either "fully hereditary" - totally impossible to perform for someone not from the bloodline - or not hereditary at all. Some of the "fully hereditary" skills - namely, dojutsu eyes - can still be transplanted onto another body, even if the person receiving the eye has no blood tie whatsoever with the donor, even if he is from a different geographical zone (Ao, the Kiri guy owning a byakugan, comes from an island, which should be relatively isolated and therefore particularly different genetically) without reject or the new owner being unable to use it due to chakra differences.
              * combined elements (such as ice, wood, etc) being hereditary implies that affinities for the two normal elements combined to form the kekkei genkai (water and wind, water and earth, etc) should also be hereditary for bloodline-owners. Why would they only be hereditary if they are to be combined?
              * some ninjas (Naruto) are said to have more chakra than others, others (Sakura) to be particularly impressive talent in things like genjutsu or medical skills, without being a member of a bloodline. Why wouldn't those talents be hereditary too?
              * if hereditary skills are the only skills being hereditary, how did they appear? Let's put the sharingan aside and speak about combined elements. A kekkei genkai appearing would mean new allele(s) appearing through mutation. Even with the easiest, simplest case - the kekkei genkai being bound to one gene, and the mutated allele being dominant - if the two base elements necessary to use the kekkei genkai weren't hereditary to begin with, how wan the kekkei genkai be transmitted?
              * Countries and villages have names related to one or two elements. The kekkei genkai follow this logic, more or less (the Uchiha's fire skills, the Senju's mokuton, the Yuki's ice, the scorch element of the Sand), but most Leaf-nin don't (compare the water theme among Kiri ninjas with the fire or wood theme among Konoha ninjas, for instance). Which has me screeching "Konoha-sue" too often for my taste.

Fanon reactions that have me rolling my eyes:
              * "Incest is gross! Ninjas with bloodlines are totally not having incestuous reproduction!"
...Okay, let's be serious for a minute here.
Bloodline skills being hereditary means that at some point or another, they appeared through mutation. Best case scenario - which, I must say, I find highly unlikely - the bloodline abilities are bound to one gene and one dominant allele (allele = a version of a gene; dominant allele = an allele that expresses itself in all cases, as opposed to a recessive allele, which only expresses itself when coupled with another recessive allele). The allele having appeared through mutation would mean that the parent owning it would be very likely to have one mutated allele and a non-mutated one.  The parent with the mutated allele (and another non-mutated one) would reproduce with another person owning two non-mutated alleles. Their children would have a 25 % chance of inheriting the bloodline. Without inbreeding, their grandchildren would have a 6,25% chance of inheriting it. Their great-grand-children? 1,625% chance. Etc. (With each generation having 1/4 of the chances their parents had of inheriting the bloodline.)
And that was the best case scenario. Which is highly unlikely given the complexity of the bloodlines we've seen in the series so far. (I think they probably take two or more genes having the good alleles, and some of these alleles might very well not be dominant.) Oh, and I conveniently ignored the possibility of one of the non-mutated alleles being incompatible with the bloodline (that is to say, another dominant allele which, combined with the mutated one, creates a "failed" version of the bloodline).
I'm not saying that all bloodline clans always actively practice brother-sister incest in the long run. I just find it very likely that they resorted to it at some point, at least at the beginning of the bloodline. And if they didn't, selective cousin-cousin incest would be necessary to keep the bloodline - that, and sending the clan members without the bloodline away from the clan, through death, marriage or the lack of marriage.
Oh, and I find very unlikely that ninjas could be stopped by the "incest is gross!" taboo if their bloodline was at stake. Even though Kishimoto might disagree with me.
              * "Bloodline clans would never practice incest, because then they'd risk developing defects together with their bloodlines!"
...okay, I know Kishimoto helped you a damn lot with forgetting this but. We. Are. Speaking. About. Ninjas. And real ninjas? Were mercenaries and assassins. With no honor. And in the Naruto world? Ninjas are the army. They canonically live for their village, and their village exists to make their country powerful.
So. Have you ever heard of infanticide? Like, killing the babies that don't fit your standards? Such as girls when you wanted a boy or babies with defects, for instance. It happens in the real world, people. And bloodline clans are ninjas, and they also have terrible reputations among other ninjas or in their countries - did it ever occur to you that maybe there were other reasons for that than them serving their country during war time?
Edit: besides, even if a clan didn't resort to infanticide, sending all of their children in ninja missions would statistically do the trick (it might be less infallible, but I heard that natural selection was a rather efficient counter against the defects resulting from inbreeding).

...Did I mention how much I love the unfortunate implications of hereditary magical skills in mangas?

Headcanon:
              Most clan skills are more or less hereditary. Granted, not always in the sense of "impossible to copy for anyone else", but I think most clans have unusually high affinities for their skills (the most fitting body type, the most fitting elemental/ type of jutsu affinities, unusual talent in their skills areas, natural higher resistance to secondary effects, etc). And apart from those goddamn Uchiha-sues, I think it would be rather rare to have somebody with the exact same affinities for the clan's skills. So they could be imitated, but outsiders wouldn't be able to reach clan members' level. Or they would die from secondary effects (think about the Akimichi skills, for instance).
              Bloodlines are developed through human breeding and selection of clan members. At best, it implies arranged marriages between cousins and marrying clan members who don't own the bloodline outside of the clan. At worst, it implies brother-sister incest and infanticide. And other horrible things, depending on the bloodline's particularities.
              Also, screw Konoha-sue, not all bloodlines come from its Sage of the Six Paths. Some clans - those from Kiri because of island's isolation, those from Suna because of desert isolation, those from Kumo because of the mountains, etc) have different, older roots. The competition of the Uchiha and Senju, and later, the creation of Konoha only prompted those clans to develop their abilities further and then form other ninja villages.

Oh, and since I love to rant about the possibilities of hereditary skills / speak of my role-play OCs.
(Horrible) things I role-played:
              * A clan with a functional but incomplete kekkei genkai (aka switching from one element to the other really really fast instead of properly using both at the same time - which allows them to use only one hand for their skill).
              * Skills with secondary effects and clans with hereditary characteristics countering said secondary effects, therefore allowing them to survive skills that would kill other ninjas should they try to steal those skills.
              * Clans actively practicing infanticide, sending their women to fuck with outside ninjas and having their men buy whores who fell pregnant with their offspring, promoting inbreeding among cousins, and living in autarky to survive the hate and murder attempts of basically everyone not clan-born. (Guess which country they came from?)
              * A clan with a bloodline still in development, actively practicing random breeding (rejecting marriage and having bastards with other ninjas to keep only the most successful breeding), selection through death or reproduction-ban and reinforcing of their bloodline through brother-sister incest practices.
              * A village launching a long-term plan to retrieve and recreate its former bloodlines, looking for bastard offspring of extinct clans, assembling said people, arranging marriages among them, then arranging marriages among their children.
              * A little girl with a newly mutated gene giving her a new, still unnamed dojutsu, suffering a lot of accidents because of it, then being helped to develop it, and later having to transmit it to an offspring.
              * A sect using a different form of natural chakra (which was created before sage-mode appeared in the manga) - basically, they use natural chakra which has already taken a nature, as opposed to the chakra sage-mode extracts (it can be present in larger or smaller quantities, depending on where you use the skill). Also, their skill allows them more or less developed unusual perception skills (reciprocally, affinities for perception and a high control of chakra are required to master those skills).