Only from the mind of Martin: a perfect inbred queen
Disentangling the hard reality of inbreeding from Game of Thrones’ fantasy
For even longer than I’ve worked in human genetics, I’ve been genuinely obsessed with George R.R. Martin’s oeuvre. At this point, it’s been a solid 23 years (since the last week of January, 1999, if you must know) and counting. But even if you’ve never let your fantasy flag fly as shamelessly as a proud nerd of my caliber, it would be hard to have lived in the US for the past decade-plus without involuntarily absorbing some knowledge of the 2010’s HBO series Game of Thrones. And perhaps the books that inspired it. Game of Thrones, named for the first of Martin’s five books thus far completed (of a projected seven) is a cultural phenomenon, with the main characters making numerous appearances on Saturday Night Live, Late Night With Seth Meyers, Conan, etc. The series finale was HBO’s most watched episode of any show ever (with nearly 20 million viewers), and surpassed the Sopranos as the network’s most popular offering. Three years on from that episode, the first of HBO”s projected six or seven spinoff series has finally debuted; House of the Dragon depicts a civil war within the fictional Targaryen royal family and reintroduces us to the land of Westeros, with its reassuringly familiar faux-medieval kingdoms rendered unforgettable by their startlingly strange and otherworldly customs.
With Martin’s vision back in the cultural foreground, Game of Thrones’s overstuffed menu of transgressive themes is likely to spill into polite conversation again, in particular the intersection of sex and violence that was a signature feature of the original series. To be sure, the explicit depictions of rape and murder hew closely to the source material, whose brutal, grim affect could hardly contrast more starkly for example with the high-minded and sanitized tone of J. R. R. Tolkien’s Lord of the Rings (and candidly, if you haven’t consumed both, I can assure you that Martin’s books are more brutal than the television series ever was). And yet sticking out like a sore thumb in Game of Thrones’ otherwise largely conventionally medieval world is the acceptance of royal incest, more reminiscent of Pharaonic Egypt than Middle Ages Europe. One of Game of Thrones’ primary protagonists, the Targaryen princess Daenerys Stormborn, is herself the product of two generations of brother-sister marriage. Originally betrothed to her own brother, the series closes with Daenerys in a relationship with her nephew (who is genetically nearly her full brother). The Targaryen family is descended from a lost race of dragon-riders, whose ability to control the beasts is genetically encoded. This is clearly a critical ability for would-be world conquerors. Perpetuating the innate aptitude to tame and ride dragons is cited as a rationale for the practice of marriage between first-degree kin. And another brother-sister affair outside of the Targaryen lineage also plays a significant role in Game of Thrones’ first season plot.
A charitable explanation of this taboo practice’s ubiquity in Martin’s stories is that it reflects his obsession with pedigrees, lineages and genetics. While Tolkien invented languages as readily as other authors describe a vista, Martin tends to fixate on the minutiae of heraldry and the genealogy and physical and mental traits passed down over many generations among the great Houses of Westeros. Martin’s output suggests the mind of a world-builder who cut his teeth on role-playing-games. Members of Martin’s House Stark of the North are almost always described as cold, brown-haired and gray-eyed, even centuries in the past, while their rivals, the southern Lannisters of the Rock are invariably tall, blond and charismatic, generation after generation. These sets of relatively immutable characteristics are attested in the hundreds of richly detailed family histories Martin has created for his own reference, whose minutiae seep tantalizingly out into both canon and semi-canon (AMA’s, etc.) works ancillary to the books in the series. This corpus of background source material includes biographical sketches of individuals who lived centuries before the books’ events and whom readers will never encounter in the narrative, even in passing. For example, Daenerys’ long-dead great-grandmother is Betha Blackwood, whom Martin gives dark hair and eyes and a fiery spirit. The persistence of specific family traits across centuries, sometimes even millennia, is artistic license and suggests somewhat different genetics from what prevails on our planet. The same is true of the ubiquity of close-kin incest as a persistent cultural feature. While there are biologically solid reasons for incest to be rare or considered aberrant in our world, in Martin’s telling it reinforces the strength of a royal family, rather than leading it down the path to bodily degeneration and extinction as our species’ history and our command of science lead us to expect.
Aside from magic and fire-breathing dragons, inbreeding’s non-tragic outcomes are one of the most unrealistic aspects of Game of Thrones. In the HBO series, Daenerys Stormborn is portrayed as a healthy and attractive young woman, and described as such in the books. But this is very implausible due to her less-than-stellar genetics. Not only are Daenerys’ parents full siblings, her grandparents were also full siblings (preceded by three generations of outmarriage). As Daenerys was the product of two generations of full siblings breeding, she has only two grandparents, and two great-grandparents, as opposed to the normal complements of four and eight. The likelihood that a human product of two consecutive generations of sibling marriage would be healthy and hale, let alone strikingly beautiful, is, shall we say, vanishingly low.
Most people know this intuitively, but what’s the science behind this truth? Why is inbreeding bad exactly? And why is sibling mating so much direr than cousin mating? If all humans descend from the same common ancestors, aren’t we all inbred at some point? To answer these questions, we need to go back to the beginning, to genetic first principles.
Heredity comes from genes
In Steve Pinker’s The Blank Slate, he discusses the Westermarck effect, where children who were not biological relatives but raised together still tend not to enter into sexual relationships as adults. The Westermarck effect is posited to be an evolutionary adaptation that confers benefit by discouraging sexual relationships between siblings, given that they are usually raised together in the same household. The aversion to incest is also reflected in cultural norms and mythologies across many societies, from the horror of Oedipus marrying his mother to the old wives’ tales that your children will be monsters if you marry your cousin. That’s because humans have a natural “folk biology” that guides us as we navigate the world around us. We categorize, we systematize and we look for patterns. We recognize dangerous animals and poisonous plants. Nourished by these instincts about what to prefer and avoid, humans were equipped to successfully breed animals and domesticate plants thousands of years before understanding the science of genetics or even positing a formal theory of heredity. We comprehend naturally that the offspring of two parents tend to resemble the parents; we don’t have to be taught this.
But intuitive heredity runs up against limits (like intuitive astronomy, which begat astrology). When Charles Darwin published On the Origin of Species in 1859, his conjecture was that natural selection upon heritable variation resulted in numerous adaptations that led to the diversity of life. Darwin’s ideas took the world by storm, because of their crystal clarity and explanatory power. Nevertheless, the theory left holes for later scientists to plug.