So, Incest ending impossibru?

[The_Great_Galendo]

Well when you got information from the novels as this quote,

"As I was saying... Onii-sama and I are true siblings. Or at least that's what it says on the records, and DNA tests have always confirmed that relation."

it doesnt leave much room for speculation. Regardless of how rare it might be with a year/less than a year between births. I truely welcome you to debunk DNA tests that the author meantion. The way Miyuki phrased it indicates, at least to me, that thier sibling status has been questioned within the novel world at an earlier point to such an extent that DNA tests were needed.

I'm aware of that, but DNA tests would also be easy to debunk in-novel. I'm guessing it would take about a paragraph to do so. Remember that the Yotsuba are known masters of information control/manipulation, and that they have a very vested interest in having Tatsuya believe that Miyuki is his sister. (It's also worth noting that they do not have an interest in having Miyuki believe that Tatsuya's her brother, and in fact they discourage her thinking of him that way as much as possible. Somewhat telling, I think.)

Again, that was the point that I was trying to make: that the author can easily jump either way. Right now, I think the evidence leans more towards not-siblings than true-siblings, and I think the story would end up being better if that were the case, but it could fairly easily go either way. Just don't be too surprised if eight or ten novels from now it turns out that the DNA tests were faked after all.

[SinsI]

I'm aware of that, but DNA tests would also be easy to debunk in-novel. I'm guessing it would take about a paragraph to do so. Remember that the Yotsuba are known masters of information control/manipulation, and that they have a very vested interest in having Tatsuya believe that Miyuki is his sister. (It's also worth noting that they do not have an interest in having Miyuki believe that Tatsuya's her brother, and in fact they discourage her thinking of him that way as much as possible. Somewhat telling, I think.)

Again, that was the point that I was trying to make: that the author can easily jump either way. Right now, I think the evidence leans more towards not-siblings than true-siblings, and I think the story would end up being better if that were the case, but it could fairly easily go either way. Just don't be too surprised if eight or ten novels from now it turns out that the DNA tests were faked after all.

Not that it would matter, anyway. It is a world with Magic, with advanced technologies from quite a distant future, with blatant eugenics programs, with main hero being a mix of Einstein, Leonardo da Vinchi, Nicola Tesla, Shiva and Jesus.

So maybe all the problems with incest aren't worth a bit, as they can be instantly fixed with some retrovirus therapy. So the stigma of incest is akin to their taboo against exposed skin, and has long lost all foundations behind it.

[Niflheim]

I'm aware of that, but DNA tests would also be easy to debunk in-novel. I'm guessing it would take about a paragraph to do so.

I'm not stoping you from doing this easy debunk, based on the info we got from the novels. By all means go right ahead, make it as long as you need.

Remember that the Yotsuba are known masters of information control/manipulation, and that they have a very vested interest in having Tatsuya believe that Miyuki is his sister.

Please tell me what very vested interest they have in him believing she is his little sister? I'm intrigued as to your reasoning behind this. How, for arguements sake that they arent siblings, would the Yotsuba even find this one in a million child at the tender age of 6 when it doesnt show any signs what so ever for an affinity to true magic? Now, for arguements sake (again), I'll give you the massive assumption that they did find this child. But doing so you run into the question of why would they raise this child into believing that she is his sister? The purpose of him is that of a 'Guardian', they arent meant to be family to begin with so why this time? As it is stated by Maya later on, a female guardian is more suited for a female, there is no logcial reason to make the boy child the 'guardian' of a female as well as pushing a brother-sister relationship onto them if all they want is the powers he has. They can just take him in, train him, use him as they see fit.

(It's also worth noting that they do not have an interest in having Miyuki believe that Tatsuya's her brother, and in fact they discourage her thinking of him that way as much as possible. Somewhat telling, I think.)

It is only telling if your base thought actually had any ground in the truth as to 'how' she should address Tatsuya.

But, before that……Miyuki-san, stop calling Tatsuya ‘Onii-sama’. I don’t really mind in public places and the like where the presence of others can’t be helped, but when alone with only the Yotsuba, you should not be treating Tatsuya like your brother."

In the presence of only Yotsuba 'onii-sama' is out of the window, rest of the time it is allowed. So how does that translate to discuraging her to see him as something other then her brother? They live on thier own and have virtually no interaction with recognized Yotsuba family members.

Again, that was the point that I was trying to make: that the author can easily jump either way. Right now, I think the evidence leans more towards not-siblings thn true-siblings, and I think the story would end up being better if that were the case, but it could fairly easily go either way. Just don't be too surprised if eight or ten novels from now it turns out that the DNA tests were faked after all.

Your point rest on a set of assumptions made to fit your theory, you even go as far as nearly speaking for the author in your original post. Neither of your assumptions thus far can be validated with things we know from the novels, or by logical reasoning. The only evidence we have to thier relationship is what we are give on black and white in the novels. Rest is just pure baseless speculations and assumptions.

Now since assumption is the name of the game, I honestly loath making baseless assumptions, I'll make a tiny one myself to give more strength to the DNA proof and "shatter" the Yotsuba information control bit. My assumption is based on the following quote.

... but even Tatsuya had doubted not just once or twice whether they were blood-related or not.

We know he is Silver and all the facilities he has access to as Silver. It isn't that far a stretch of the mind that within these facilities he can run a simple DNA test or two. Nice and simple.

Lastly I'll make it clear I'm not denying you your opinion or wishes, it is just that your original post pretty much called anyone not seing what you see as a smuck.

[SinsI]

Please tell me what very vested interest they have in him believing she is his little sister? I'm intrigued as to your reasoning behind this. How, for arguments sake that they aren't siblings, would the Yotsuba even find this one in a million child at the tender age of 6 when it doesn't show any signs what so ever for an affinity to true magic? Now, for arguments sake (again), I'll give you the massive assumption that they did find this child. But doing so you run into the question of why would they raise this child into believing that she is his sister? The purpose of him is that of a 'Guardian', they aren't meant to be family to begin with so why this time? As it is stated by Maya later on, a female guardian is more suited for a female, there is no logical reason to make the boy child the 'guardian' of a female as well as pushing a brother-sister relationship onto them if all they want is the powers he has. They can just take him in, train him, use him as they see fit.

I think it has something to do with Miyuki being the sole being that can control Tatsuya - he is their greatest and most dangerous asset, after all.

[Niflheim]

I think it has something to do with Miyuki being the sole being that can control Tatsuya - he is their greatest and most dangerous asset, after all.

Still doesnt explain why they have to coax him into thinking he got a little sister. There is no need to trick them into thinking they are brother and sister for the sake of Miyuki acting as a limiter to hide his power. A more standard Guardian/Servent and Master relationship is more suited, since it runs less risk of creating complications.

This line of thought also springs the follow up of why would they need to hide his powers? I mean, what they did is either classfied as human experiments and illegal or close enough to it. I'm not sure if this is actual stated but I got a vague memory of it being explained as such.

She used the forbidden Non-Systematic Magic 'Mental Design Interference', forcibly altering the area in the consciousness, most likely to create strong emotions called the limbic system by inputting a Magic Calculation Model, creating an artificial Magician. The one who designed this experiment was Yotsuba Maya, who had recently been appointed the head of the Yotsuba Family, while the one who conducted this experiment on her six year old son that had no magic skills was Shiba Miya.

Guess it depends what value forbidden carries. But if it is forbbiden to use Miyas powers the way they did in what is called an experiment we could conclude that what they did is illegal and needs to be hidden. Thanks to Suzune's family story we know human experiments are reason to lose your number. However this still wouldnt explain why they would trick them into believing they were siblings insteed of just Guardian and Master.

[The_Great_Galendo]

I'm aware of that, but DNA tests would also be easy to debunk in-novel. I'm guessing it would take about a paragraph to do so.

I'm not stoping you from doing this easy debunk, based on the info we got from the novels. By all means go right ahead, make it as long as you need.

My point is that the only information we have about the DNA tests comes from a line of dialogue spoken by a character, not from the author himself -- and what one character can say, another can easily refute. This happens all the time in stories (e.g., "Obi-wan never told you what happened to your father." / "He told me enough. He told me you killed him."), so spoken dialogue isn't something I put a whole lot of emphasis on. Let the author himself say that there have been unadulterated DNA tests and my objections will evaporate, but for now, this isn't a piece of evidence I feel to be particularly strong.

Of course, generally, what characters say should be relied on unless there's information to the contrary that they might be lying or wrong. We've seen enough from the siblings' point of view to safely exclude the 'lying' part, but there's still a lot of information to support the 'wrong' idea -- including, ironically, in the very line you quoted in your earlier post. Here's that quote again:

... but even Tatsuya had doubted not just once or twice whether they were blood-related or not.

Note three things: 1) This is the author saying this, not a character. Therefore it automatically has more veracity than what Miyuki said, even though she's generally a reliable source. Tatsuya has definitely had doubts. 2) This quote comes at the very beginning of the work. When planning to do an about-face on a previously established topic (in this case, the sibling status of Tatsuya and Miyuki), it's important to plant the seeds to the alternate possibility well in advance of the actual reveal so that the audience doesn't feel like the change came out of nowhere. You don't get much earlier than Volume 1, Chapter 1. And finally, 3) There are more examples of this 'maybe-not-siblings-after-all' seed-planting throughout the books. I'm too lazy to look up more instances, but they're there. I seem to remember a particularly telling one at some point during the Nine School's Competition arc, for what it's worth. Probably in the fourth volume.

Please tell me what very vested interest they have in him believing she is his little sister? I'm intrigued as to your reasoning behind this. How, for arguements sake that they arent siblings, would the Yotsuba even find this one in a million child at the tender age of 6 when it doesnt show any signs what so ever for an affinity to true magic?

First, as to how they found him, it was established that the Yotsuba did a bunch of human experiments on magic enhancement/production/whatever it was exactly that they did. (Again, too lazy to try to find an actual quote, but I seem to remember it being mentioned explicitly in the flashback volume and alluded to in other volumes.) If you run tests/experiments on a million children, it's not at all surprising if you hit a one-in-a-million jackpot.

Second, as to the vested interest they have in believing that Miyuki's his sister: remember that the Yotsuba eliminated every emotion that Tatsuya possessed except for filial love. They therefore have a very powerful weapon who has no particular reason to wish them well whose loyalty they absolutely must ensure, and filial love is the only lever they have. Without someone loyal to the family being his sibling, they're in a world of hurt. Therefore, they've a vested interest in him believing that she's his sister.

In the presence of only Yotsuba 'onii-sama' is out of the window, rest of the time it is allowed. So how does that translate to discuraging her to see him as something other then her brother? They live on thier own and have virtually no interaction with recognized Yotsuba family members.

I figure them allowing her to call him 'brother' when in public was a nod to necessity, not something they were happy about. "Onii-san" would be the proper way for her to address him. I imagine they're less happy about the "-sama" part, but note that they'd be just as unhappy with it even if Miyuki and Tatsuya are actually siblings, so the issue doesn't add anything to the 'siblings or not siblings' debate one way or the other.

Your point rest on a set of assumptions made to fit your theory, you even go as far as nearly speaking for the author in your original post. Neither of your assumptions thus far can be validated with things we know from the novels, or by logical reasoning.

Hopefully this expanded post has made my position clearer. (I'm also not sure how you think I'm speaking for the author, unless you refer to my statement that it's pretty clear to me that he's keeping the topic open enough to go either way.) To be even more clear, here's a brief list of what I feel are the most telling points [caveat: that I can think of at the moment] in favor of either argument, along with a parenthetical comment on how difficult I feel it would be to explain away/alter the given point in the books:

Arguments on the pro-siblings side:
*They believe they're siblings (difficulty to alter: Medium to Difficult. If not for the relationship being questioned already, it would be Very Difficult)
*Shared high magical ability (difficulty to explain: Medium as of V9C6, where I'm at currently, but expected to drop to Easy if rumors I've heard about yet another magically gifted Sakura-series character to be introduced are true. If a significant fraction of the Yotsuba's research subjects have high magical ability, then Tatsuya having high magic ability is much easier to explain)
*Mentioned DNA tests (difficulty to alter/explain away: Easy)

Arguments on the not-siblings side:
*Different treatment by the Yotsuba (difficulty to alter/explain: Nearly Impossible, though admittedly this is because I find the whole "But he's just a Guardian/doesn't have a 'true' magic ability" explanation terribly inadequate.)
*Unnaturally close birth dates (difficulty to explain: Medium to Difficult, though perhaps this is only an issue because the author doesn't realize the improbability)
*Physical descriptions [e.g., that it's been stated that they don't look much like siblings] (difficulty to explain: Easy)

Again, I think you can make a pretty good argument for either side -- which was the point of my original post. I just think that, at the moment, the not-siblings side has the more difficult to alter arguments, making it more reasonable for the story to go in that direction.

Now since assumption is the name of the game...We know he is Silver and all the facilities he has access to as Silver. It isn't that far a stretch of the mind that within these facilities he can run a simple DNA test or two. Nice and simple.

Except that Tatsuya's a CAD technician, not a doctor or biologist. Expecting him to have the equipment to run a DNA test in his lab would make about as much sense as expecting a software development firm to have the tools to run one. Not all labs have the same tools, and there's no reason to think that a CAD lab would have a DNA testing machine.

Lastly I'll make it clear I'm not denying you your opinion or wishes, it is just that your original post pretty much called anyone not seing what you see as a smuck.

Insulting anyone really wasn't my intent. Maybe I could have worded my position better. I'm just surprised that everyone else in this thread seems to take as given that they're actually related, when it seems pretty clear to me that the author hasn't come down firmly yet on one side or the other. I'm also guessing that something like two-thirds or three-quarters of Japanese manga/light novels/anime in which the main pairing start off as siblings end up revealed to be not actually siblings eventually, so if you're a fan of Beyesian statistics, you should probably be prepping yourself for that sort of ending anyway. Of course, that's in addition to all the in-story evidence that suggests they might not actually be siblings.

[Niflheim]

My point is that the only information we have about the DNA tests comes from a line of dialogue spoken by a character, not from the author himself -- and what one character can say, another can easily refute. This happens all the time in stories (e.g., "Obi-wan never told you what happened to your father." / "He told me enough. He told me you killed him."), so spoken dialogue isn't something I put a whole lot of emphasis on. Let the author himself say that there have been unadulterated DNA tests and my objections will evaporate, but for now, this isn't a piece of evidence I feel to be particularly strong.

I was of the idea that everything written in a work is from the author him/herself. It is a world he/she created, everything in it is his/hers and follow his/hers thoughts and wishes. Now trying to pin certain lines as individual characters personal thoughts excluded from the author, honestly how the hell would that even work? What you are doing right now, since there is nothing written by the author to debunk or refute thier sibling relation, is trying to move the goalposts to suit your need. Even your "argument" is constructed to suit your need. Even IF another charcter CAN say that the DNA tests are faked thus far NO ONE has so there is no information what so ever in the realm of the fictional world to say that they are not blood related siblings. Until the day the author, if he planed for it, changes thier blood relation thier current status is cannon and fact, regardless of what we readers might feel. Frankly this entier discussion should be over there.

Of course, generally, what characters say should be relied on unless there's information to the contrary that they might be lying or wrong. We've seen enough from the siblings' point of view to safely exclude the 'lying' part, but there's still a lot of information to support the 'wrong' idea -- including, ironically, in the very line you quoted in your earlier post. Here's that quote again:

... but even Tatsuya had doubted not just once or twice whether they were blood-related or not.

Note three things: 1) This is the author saying this, not a character. Therefore it automatically has more veracity than what Miyuki said, even though she's generally a reliable source. Tatsuya has definitely had doubts. 2) This quote comes at the very beginning of the work. When planning to do an about-face on a previously established topic (in this case, the sibling status of Tatsuya and Miyuki), it's important to plant the seeds to the alternate possibility well in advance of the actual reveal so that the audience doesn't feel like the change came out of nowhere. You don't get much earlier than Volume 1, Chapter 1. And finally, 3) There are more examples of this 'maybe-not-siblings-after-all' seed-planting throughout the books. I'm too lazy to look up more instances, but they're there. I seem to remember a particularly telling one at some point during the Nine School's Competition arc, for what it's worth. Probably in the fourth volume.

Where is the information, quote it from the actual written work, that would indicate that they are anything but blood related siblings? If this information is so abundant as you make it seem there should not be any problems at all to give me/us 5-6 written cases by the author himself. Atm you are making claims without backing them up.

Lets extend that quote, since you are looking at it entierly out of the context where it is written, while I just used it as part of a constructed (and thus invalid argument in the assumption game) reasoning.

Even if it were only partially, they should still inherit the same genes, but even Tatsuya had doubted not just once or twice whether they were blood-related or not.
"If you put it that way... uhn, you do look alike. Shiba-kun is quite the hunk as well. It just kind of feels like your features can't resemble any more than that."

His doubts are born from simple genetics, while they have some similer features for example thier affinity to magic is like night and day. Thats from where his doubts came. Not some super hidden plot to make him believe he has a sister.

Now your 3 points.
1) Aside from the fact that it doesnt give or take more or less value to a piece of information if it is narrated or spoken by a character (both cases are still the thought of the same author) you isolated that one line out of its context in the novel. It isn't words Tatsuya says to Erika and Mizuki but it is still his silent thought during thier ongoing conversation, hence they are his and not some strange seperation you want to make between characters and author. This is, like i said above, moving the goalposts to suit your need.
2) You are still looking at that one line out of context. The entier conversation that line is from explains why he had at some point doubts towards thier blood relation. You have yet to provide a singel piece of information from the written work to indicate anything other than that they are real siblings. You are spinning words like a champion, but thus far spinning is also all you are doing.
3) You claim there is examples of this not blood related relationship, but admittedly to lazy to actually provide me/us with said examples. So, does this mean you realise you actually don't have any and this is only in your head? Lucky for me/us is you meantion volume 4, the one with very stand outish interactions between Tatsuya and Miyuki. Volume 3 isnt much better for your sake either, incase you plan to fall back on that you meantioned the nine schools competition arc.

First, as to how they found him, it was established that the Yotsuba did a bunch of human experiments on magic enhancement/production/whatever it was exactly that they did. (Again, too lazy to try to find an actual quote, but I seem to remember it being mentioned explicitly in the flashback volume and alluded to in other volumes.) If you run tests/experiments on a million children, it's not at all surprising if you hit a one-in-a-million jackpot.

Second, as to the vested interest they have in believing that Miyuki's his sister: remember that the Yotsuba eliminated every emotion that Tatsuya possessed except for filial love. They therefore have a very powerful weapon who has no particular reason to wish them well whose loyalty they absolutely must ensure, and filial love is the only lever they have. Without someone loyal to the family being his sibling, they're in a world of hurt. Therefore, they've a vested interest in him believing that she's his sister.

So many words, and yet you didnt answer either of the two simple questions. Again (this feels repetative by now) you are moving the goalposts to dodge the questions at hand, and they didnt change even after what you just wrote. I won't go as far to claim that they only performed these enhancment operations on family members, but from a logical stand point it makes sense. The fact that we know virtually nothing about the structure and size of the Yotsuba family, the very nature of these experiments seems to be something kept small scale and on subjects with a known blood line. One million children is an outrages and absurd exaggeration, even as such your are claiming large scale systemetic search and experimentation on children, I'll requier an actual source on that.

I'll make it simple for you.
What interest does the Yotsuba have in an ungifted child that is a failure as a magician by thier own defenition?
Why would they need to imprint a fake sibling relationship to secure a random childs loyalty? A child they have taken care of since it was old enough to remember.

I figure them allowing her to call him 'brother' when in public was a nod to necessity, not something they were happy about. "Onii-san" would be the proper way for her to address him. I imagine they're less happy about the "-sama" part, but note that they'd be just as unhappy with it even if Miyuki and Tatsuya are actually siblings, so the issue doesn't add anything to the 'siblings or not siblings' debate one way or the other.

It does add to the debate, since her behaviour does a 180 turn in how she addresses and in what terms she thinks of Tatsuya. Up until she gets shot she thinks of him as Ani or brother, pretty neutral. This is such a strong pattern in her that when she expresses a desire to watch Tatsuya go to the military base in vol 8 she stumbled when pronouncing Nii-san. This is explained right away with that she always thinks of him as 'brother' or 'that person'. After she gets shot her entier behaviour changes radically, she freely refers to him as onii-sama infront of her mother and it became her "catch phrase" entierly. Unless they were actual siblings you got one heck of a problem here to explain as well, so I can see why you want to ignore it.

Hopefully this expanded post has made my position clearer. (I'm also not sure how you think I'm speaking for the author, unless you refer to my statement that it's pretty clear to me that he's keeping the topic open enough to go either way.) To be even more clear, here's a brief list of what I feel are the most telling points [caveat: that I can think of at the moment] in favor of either argument, along with a parenthetical comment on how difficult I feel it would be to explain away/alter the given point in the books:

Arguments on the pro-siblings side:
1*They believe they're siblings (difficulty to alter: Medium to Difficult. If not for the relationship being questioned already, it would be Very Difficult)
2*Shared high magical ability (difficulty to explain: Medium as of V9C6, where I'm at currently, but expected to drop to Easy if rumors I've heard about yet another magically gifted Sakura-series character to be introduced are true. If a significant fraction of the Yotsuba's research subjects have high magical ability, then Tatsuya having high magic ability is much easier to explain)
3*Mentioned DNA tests (difficulty to alter/explain away: Easy)

Arguments on the not-siblings side:
1*Different treatment by the Yotsuba (difficulty to alter/explain: Nearly Impossible, though admittedly this is because I find the whole "But he's just a Guardian/doesn't have a 'true' magic ability" explanation terribly inadequate.)
2*Unnaturally close birth dates (difficulty to explain: Medium to Difficult, though perhaps this is only an issue because the author doesn't realize the improbability)
3*Physical descriptions [e.g., that it's been stated that they don't look much like siblings] (difficulty to explain: Easy)

This is a "big" one, but heck I've gone this far so lets take it all the way home.

Your position has been clear from the start, you provide no sources or quotations to back up your claims and you keep pushing the goalposts ontop of that. To make it simpler to answer I gave your points numbers in the quote.

Arguments on the pro-siblings side
1) They believe they're, because to our knowledge they are siblings. Nothing points towards that they wouldnt be. Not a hint of anything else at this point cross 11 volumes, doubt volume 12 that is coming in about a week will say otherwise as well.
2) Factually wrong. They don't share a strong affinity to magic. Tatsuya can't even freely use magic he himself designed all the time. If they truely shared this there would never have been the need for the magic operation that made him into what he is in the first place. The second generation Sakura series doesnt indicate anything except that an individual shows enough power to become a Guardian (this is explained by Miya in refrence to the result of the magic operation on Tatsuya)
3) This is a piece of information that orignially should have ended this entier debate until the day the author decide to change the status quo of it.

Arguments on the not-siblings side
1) Different treatment for different people, not sure what this would indicate other then what it is. It becomes even more obvious that they would be treated differently when one is a talented successor candidate from an early age and the other is viewed as a failure. Your view on the stated defenition on what a magician is by the Yotsuba doesnt change the merit of it in the realm of the fictional world. So this really doesnt prove anything for your part.
2) This is the only real point you got backing your case atm. That is despite that in theory it is well within the realm of possibility. Why you don't see this more in "the real world" if I'd take a wild guess stems from practicality rather then what is physically possible. It pretty much boils down to the recovery rate of the woman in question. The big joker here, in terms of this story, is to what extent healing magic can help with the recovery.
3) Physical description isnt really a strong indicator for blood relationships. That it's been stated that they don't look much like siblings doesnt prove they arent either. They didnt inherit magic similarly so that thier looks, aside for some features, would be different isnt much of a stretch. I won't provide pics but can't say me and my sister look much alike to the degree that people have asked if we really were sibllings.

Except that Tatsuya's a CAD technician, not a doctor or biologist. Expecting him to have the equipment to run a DNA test in his lab would make about as much sense as expecting a software development firm to have the tools to run one. Not all labs have the same tools, and there's no reason to think that a CAD lab would have a DNA testing machine.

I shouldnt even respond to this because we will enter the world of assumptions in an already assumed scenario.
This is a case of read what the other wrote. I didnt say that he would run the tests himself, or that he would do it in his own lab. I only spoke of the facilities he could have access to as Silver and part of FLT. That they would have close ties to a hospital isnt that odd, that he could ask for a small favor at said hospital to check sample A and sample B isnt that far of a stretch to me.

Insulting anyone really wasn't my intent. Maybe I could have worded my position better. I'm just surprised that everyone else in this thread seems to take as given that they're actually related, when it seems pretty clear to me that the author hasn't come down firmly yet on one side or the other. I'm also guessing that something like two-thirds or three-quarters of Japanese manga/light novels/anime in which the main pairing start off as siblings end up revealed to be not actually siblings eventually, so if you're a fan of Beyesian statistics, you should probably be prepping yourself for that sort of ending anyway. Of course, that's in addition to all the in-story evidence that suggests they might not actually be siblings

There are lies, damned lies and statistics. I was honestly wondering when I was going to be allowed to use this. Can I say finally? Besides you are most likely thinking of Bayesian probability rather then Bayesian statistics. So I'm not sure what i should get myself ready for, I've never been against an incestuous "ending" to begin with. What I'm firmly against is when peoples strong opinions that lack credibility takes root as fact within a fan community.

[Sashiko]

Excuse me but, I am going to offer my own two cents in to why the two are siblings.

1. Differences in their appearences
The primary two clear differences in how they look are:
a. Miyuki is beautiful and Tatsuya is plain
b. Miyuki is pale and doesn't tan and Tatsuya tans easily

Yet, despite these differences, a number of perceptive people see an immediate family resemblence
a. Mizuki chapter 1 volume 1 - through pushion sensitivity
b. Erika chapter 1 volume 1-through trained swordswoman senses(see chapter 16 volume 11 for an example of their acuity)
c. Elder Kudou chapter 12 volume 4-through having taught their mother and aunt briefly

2. Differences in their powers
a. this was addressed in Untouchable--Yotsuba come in two basic types -- Miya and Miyuki are one type, Maya and Tatsuya are the other

3. The eleven month gap
a. as there is a thirteen moth gap between me and one of my siblings this doesn't bother me.
b. Miya was physically weak (Untouchable and Volume 8 ) so, it makes sense that once the Yotsuba decided she would get married and have children that they would try for as many as possible before she croaked or became incapable of having kids.
c. It was basically implied that their father was waiting for Miya to die so he could marry Sayuri during the whole marriage (chapter 2 Volume 6). So trying to speed up her death through pregnancy would make sense.

4. Miya not treating him as a son and encouraging Miyuki not to treat him as a brother.
a. Treating Tatsuya as anything but an underling is actively discouraged in the Yotsuba (chapter 2 volume 3 and throughout volume 8 )
b. it is implied in volume 8 that now that Tatsuya is completely indifferent to her, Miya is jealous whenever Tatsuya shows affection to other people
c. the idea that he was brainwashes into loving Miyuki as a sister is contradicted by Miya's testimony in chapter 14 volume 8.

Sashiko

[Niflheim]

hehe, no need to excuse yourself it's an open discussion after all, and you piqued my interest with one thing.

b. Miya was physically weak (Untouchable and Volume 8 ) so, it makes sense that once the Yotsuba decided she would get married and have children that they would try for as many as possible before she croaked or became incapable of having kids.

This isnt just for you, anyone is free to shim in. I wonder if the timeline would fit with the point of Miya's worstening health coincides with the Miyuki's birth. Basically is it her birth that triggers a downward spiral? Guess that is a tad OT but oh well.

[Sashiko]

Nifleim, the full details an Miya's condition are toward the end of Untouchable.

On a different note, do you think that there could be a half-sister showing up later on. I can't remember exactly where but there was a line about Sayuri and their father not wanting Tatsuya around their beloved daughter, so could that have referred to someone other than Miyuki?

Sashiko

[Niflheim]

Nifleim, the full details an Miya's condition are toward the end of Untouchable.

On a different note, do you think that there could be a half-sister showing up later on. I can't remember exactly where but there was a line about Sayuri and their father not wanting Tatsuya around their beloved daughter, so could that have referred to someone other than Miyuki?

Sashiko

Guess I'll give Vol.8 a reread, it is just such a drag, if there is something about that there. Can't recall there is but hey, my memory isnt what it used to be I'm close to it in the cycle anyway.

Half-sister you say, that is a thought and a curveball. I wouldn't put it out of the realm of possibilities. The marriage between thier parents wasnt exactly out of love, and thier father was decently compensated for his troubles. I won't swear on it, but unless I'm mistaken thier father continued his relationship with Sayuri even during his marriage to Miya, or at least started it up again once she became worst health wise. The only passage I've read with Sayuri is one I'm coming up to, I'll see if it is there otherwise it is in vol.10-12 in which case I haven't read it. Would be nifty if you could find the line, regardless of where it is. Though I can't see how they would have kept such a childen hidden from Tatsuya.

[Sashiko]

Um, why would you need to reread all of Volume 8 when the details are in a stand alone short story at the end of the book?

As for the line about their beloved daughter, I searched for it where i thought it was and couldn't find it so I probably misremembered the line however, I still think a half sibling will show up sooner or later.

Sashiko

[Niflheim]

Lets leave the 'why' to force of habit

Ah well, guess we can only wait and see if a half sibling pops up. Maybe it has the latent talent thier father has/had but never could make use off.

[Onanimousse]

All of you are totally forgetting that arranged marriages are quite commonplace within this setting.

Therefore any feelings he may have for any one heroine is totally irrelevant, especially considering how controlling and emotionless the matriarch of his family is. He'll marry whomever she decides for him to marry unless he kills her first.

And frankly, I don't see him ending up with Miyuki no matter how she sees him. Lina also seems very unlikely as she's a foreign military officer and I doubt either nation would like them getting together.

and you all forget about Tatsuya's gene is defective for magician.
there is high risk for having a child with a defect.

i doubt he can marry anyone from the magician community.
it's better for him to marry someone outside there. like what happened to Shizuku's parents.

Something you forgot, Tatsuya is in no way a defective magician. His mother considered him defective because he does not conform to HER view of what a magician is.
He was labeled as a defect because he "could not" use magics that are expected of stereotypical magician. There's a fine line between "can't" use and "could not" use here. He was born with 2 extremely unbalanced specialized magics that took up his entire magic calculation area. They are the reasons he could not use other magic prior to the artificial magic calc area whereas in the case that if he was born without any specialized magic and is still can't effectively use other magic, only then will he fit the label of defective.

Tatsuya wasn't born with defective magician-esque genes. On the contrary, those genes were the jackpot that Miya seeked with her selective breeding (lol) but was too blind to see for what they were. His dominion is basically over Life and Death/Creation and Destruction. If anything, any successors to his genes has more to gain than lose.

[Niflheim]

Something you forgot, Tatsuya is in no way a defective magician. His mother considered him defective because he does not conform to HER view of what a magician is.
He was labeled as a defect because he "could not" use magics that are expected of stereotypical magician.

You say others forget he isnt defective when you don't seem to recall when Miya explains to Miyuki what magic is. She doesnt only speak about what the Yotsuba consider a magician, but also broadly speaking what magic is and how it is defined.

"Magic are the techniques which modify Information bodies, and thus change phenomena. However trivial the change is, to be able to make the change at all is magic. But Tatsuya is unable to do that. All he can do is break an Information Body down, and recreate it back in an earlier state. That is not magic in its truest sense. That child, who was born without the talent to use magic in the true sense of the term in altering Information Bodies, is unquestionably a defective magician."

He simply doesnt fit the bill. You are constructing an argument when you start creating lables as "sterotypical magician", unless you can point to any source from the author that confirms there is a thing such as a "sterotypical magician" you are out on very deep water. Miya's explaination is so broad that it covers anything considered magic. He got power, a lot of it, but that is also the only thing he has.

There's a fine line between "can't" use and "could not" use here. He was born with 2 extremely unbalanced specialized magics that took up his entire magic calculation area. They are the reasons he could not use other magic prior to the artificial magic calc area whereas in the case that if he was born without any specialized magic and is still can't effectively use other magic, only then will he fit the label of defective.

There is also a "fine line" between fact and personal opinion spun as fact, called "sources". He has 2 great powers but neither of them are strictly speaking magic as magic is defined in this world. This is something you can not escape. If the powers he was born with was truely considered magic he wouldnt be where he is, not even logical does it make sense to call it magic with in this world. He wouldnt even be an irregular at a magic high school if the power he has was considered magic. The title of the work it self would be wrong.

Tatsuya wasn't born with defective magician-esque genes. On the contrary, those genes were the jackpot that Miya seeked with her selective breeding (lol) but was too blind to see for what they were. His dominion is basically over Life and Death/Creation and Destruction. If anything, any successors to his genes has more to gain than lose

There is nothing wrong with his genes, his father was picked for his high psion count and Miya was of the Yotsuba, so far so good. What they most likely sought was just strong children like Miyuki, not a dud like Tatsuya. Miya knows very well to what extent her sons power reaches, she wasnt blind to anything. His area of expertise is with Destruction and Reconstruction. It is explained what limitations Regrowth has regarding death.

But not even his ‘Regrowth’ could call someone back from death. Life and death was an irreversible cyclic process, the changing of state from ‘alive’ to ‘dead’ being purely intrinsic. ‘Regrowth’ could restore a body back to a perfect state, but the dead do not come back to life. Such an inherent truth was clearer to none other than Tatsuya himself.
Even if the heart had already stopped, the brain shut down, the throat torn open, if that was the extent of their injuries then revival was still possible. Even an instantly fatal wound, as long as rebuilding the body and restarting the circulation of blood would have had even the faintest chance of resuscitating the person, his ‘Regrowth’ could be said to give life to the dead.

Lats but not least, his future children. They will, like all other of Yotsuba blood, inherit within the two lines of magic the Yotsuba inherits from. Ofc the mothers own genes will effect this. This means that his own children may very well inherit from the mind manipulation line rather than his own.