I’ve posted on this before. So I will post again just to reiterate something: in terms of genes, Jon Snow and Daenerys Targaryen are much closer to being full-siblings than they are to being aunt and nephew.
You get different numbers depending on how deeply you look at the pedigree of the two. But their relatedness is probably above 40% and below 50%. Others have confirmed:
Yes, calculating the inbreeding coefficient from the pedigree, I calculate the coefficient of relationship between Jon and Daenerys as 43.75%.
The verbal reason without math and genealogies is simple: Daenerys Targaryen comes from an inbred lineage, and more importantly, two generations of brother-sister marriages. This means that Daenerys Targaryen and Rhaegar Targaryen were genetically much more similar than typical full-siblings. Because of this, Jon Snow and Daenerys Targaryen are much more genetically similar than typical aunts and nephews, because Jon Snow’s father was to a first approximation genetically a male and older version of Daenerys Targaryen.
George R. R. Martin has done something new in fantasy. He has created a world in shades of gray. This is in contrast to the modern template of J. R. R. Tolkien’s The Lord of the Rings, where what is good and what is evil were as clear and distinct as black and white. In addition, A Song of Ice and Fire transcended fantasy’s traditional appeal to adolescent males. This latter tendency is pretty evident in Robert Jordan’s The Wheel of Time, which was simply not moving beyond its juvenile origins by book seven or eight, when I gave up (I was moving beyond my juvenile origins by that point). It isn’t as if the Jordan-style, geared toward adolescent male virgins, can’t be done well. I’d argue that Brandon Sanderson pulls this off very competently.
One of the aspects of A Song of Ice and Fire in the books is there isn’t a Dark Lord who is the literal personification of evil. No Sauron. Even the primary antagonists become less dark with deeper exploration, and their motivations are often complex, and comprehensible in their own way.
But there is a major exception to this: Ramsay Snow and House Bolton. The Boltons are the great rivals of the Starks in the North, and before they were vassals they were kings. And they are evil in a straightforward sense without nuance. One stupid “fan theory” (these are the television show watchers) even posited that Roose Bolton was an immortal vampire.
Though Martin is careful to suggest that people should not take the antiquity of the dynasties in A Song of Ice and Fire literally, it is clear that the Bolton’s are not parvenus. Their lineage is old, and it has persisted. And yet the Boltons which are highlighted are basically without any redeeming qualities over their history. Ramsay Snow is basically the protagonist of a snuff film come alive.
When it comes to mining history perhaps the best analog to the Boltons were the Assyrians. Like the Boltons they flayed their enemies alive. The Assyrians also famously were totally destroyed by their enemies because of the ill-will their cruelty in conquest generated. Martin is a student of history, and there is no way that a lineage of such unmitigated evil could persist down the centuries. The Boltons exist as witness to the long tradition of fantasy antagonists which readers love to hate.
If you have been following Game of Thrones you have been noticing that there is a brewing romance between Jon Snow, King in the North, and Daenerys Targaryen, the aspiring claimant to her father’s Iron Throne.
Of course there is a twist to all of this: unbenknownst to either, Jon Snow’s biological father is Daenerys’ dead brother, Rhaegar. This means that Daenerys is Jon Snow’s aunt.
Long-time followers of the world of Game of Thrones are aware that incest between near relations is neither unknown nor shocking. But there is a non-trivial detail which it is important to note. Jon and Daenerys are far more closely related than typical aunts and nephews.
The reason is simple, Daenerys and her brother were the products of two generations of sibling incest. Incest results in inbreeding, and inbreeding as you know results in loss of genetic diversity. By Daenerys’ generation the coefficient of relationship between herself and her brothers was much higher than normal.
To be concrete, the coefficient of relationship of full-siblings is 0.50. That of half-siblings 0.25. Identical twins? Obviously 1.0. Another way to think about this is how much of the genome do any two pairs of individuals share in terms of long tracts of inheritance from recent ancestors. On the whole siblings share about half of their genomes in such a fashion. After two generations of inbreeding Daenerys and Rhaegar have a coefficient of relationship of 0.727 (using Wright’s method). They’re not identical twins, obviously, but their genetic relationship is far closer than full-siblings!
Dividing this in half gives 0.36 as the coefficient of relationship between Jon and Daenerys, as opposed to 0.50 for full-siblings and 0.25 for a conventional aunt-nephew. Jon and Daenerys have almost the same genetic relationship as 3/4 siblings; two individuals who share a common parent, like half-siblings, but whose unshared parents are first order relatives (full-siblings or parent-child).
Not Jaime & Cersei creepy, but still creepy.
Addendum: Though Daenerys is quite inbred, Jon is not at all. One generation of outbreeding can eliminate all inbreeding.
The Week has published a screed against the low moral quality of Game of Thrones, Game of Thrones is bad — and bad for you. Obviously there is something to this insofar as one can see a coarsening of entertainment, or at least a decline in the stylized aspects of the depiction of reality.
In some cases the shocking aspect of ancient stories is because moderns have different values. Slavery and concubinage were taken for granted during the period that the Hebrew Bible and Classical mythology crystallized into the forms which came down to us. In other cases I presume that it was unlikely that small children were going to ever read the original stories themselves, so sexual elements that might confuse were probably omitted in some oral tellings.
This is not to say that Game of Thrones is a modern masterpiece. But some of the disquieting, and frankly perverse, aspects of the narrative are only shocking if your standard is the relatively antiseptic literary fiction which one finds between the Regency and the cultural revolution of the 1960s. That is the aberration in human history, while gritty genre fiction much closer to primal human storytelling.
Wired has a piece out George R. R. Martin Doesn’t Need to Finish Writing the Game of Thrones Books. The title is needlessly provocative, as there are many good points in the article (though I understand clickbait considerations). Over the years I’ve come to expect and accept that the “great fork” is here to stay, and the books and the the television shows are in some deep and fundamental ways going to be distinct narratives (though Martin and the producers of the television show assert that their conclusion will be congruent, which I actually think may not be optimal).
But the author dismisses an important point rather flippantly:
For the last few years being able to say “Sure, yes, but the books are better” has provided a nice little dopamine rush. But beyond that thrill, what Game of Thrones fans really want is more Game of Thrones. And right now, their best bet for getting that is on premium cable.
But none of these works are on par with the world-building and richness of George R. R. Martin’s series (especially the first three books, A Game of Thrones, A Clash of Kings, and A Storm of Swords). Additionally, in the case of the Jaws and The Godfather I think most people agree that the films are far superior artistic productions to the books. And in relation to Blade Runner, most people know that Philip K Dick’s story Do Androids Dream of Electric Sheep? was only tenuously connected to the movie adaptation.
I understand that writers are sometimes given tasks or make a really good pitch on the most general terms. But if the points wouldn’t pass muster wit your high school English teacher, should they pass muster with a national magazine? In the clickbait era, probably. But I’m still here to point out that Mrs. Barry would not have approved….