[Author’s Note: This essay is being published in honor of the release of the eighth and presumably final Harry Potter movie. The article deals with the subject of demography in the fictional world of Harry Potter, but in doing so speaks about subjects that are of great and important interest far outside of that fictional world. The analysis largely supports and takes off from that in an essay found here . I strongly encourage even those authors who dislike Harry Potter, justifiably, for reasons of concern about its portrayal of heathen magical practices, to seek to glean such useful knowledge as they may apply to their own lives or the specific subpopulations they belong to, where concerns of being fruitful and multiplying are of particular relevance and the struggle to find suitable marriage partners is similarly brutal and unpleasant.]
One of the more fascinating questions about J.K. Rowling’s Harry Potter universe is the question of family histories. Some wizards and witches come from long and noble families (called “pure blood”), such as Draco Malfoy and Neville Longbottom. Other wizards and witches, including such notable ones as Lily Evans (Harry Potter’s mother) and Hermoine Granger (one of Harry Potter’s best friends) come from muggle families where no (known) magic users had been found before. Such wizards are often noted to be exceptionally brilliant. Also known as powerful and brilliant wizards are those of half-blood origin, like Tom Riddle (aka Voldemort), Severus Snape, and Harry Potter.
Related to the question of magical origin within families is the question of the anti-muggle bias of wizards. There is a longstanding prejudice against squibs (non-magic descendents of magical families) and so-called “mudbloods” (wizards and witches from “muggle” families), as well as “blood traitors” (pure-blood or mostly pure-blood families who, like the Weasleys, intermarry freely with muggle and half-blood witches and wizards). If a wizard family wanted to take control of the wizard population, what would be the best strategy? Would the “pure blood” strategy of Lord Voldemort or Lucius Malfoy or the “blood traitor” strategy of the Weasley clan be better suited to gaining control of the Wizanganot? That is the subject of this essay.
A Question Of Numbers
Let us set our parameters for exploration with a look at the numbers as they have been provided by J.K. Rowling’s novels, whether she has thought explicitly about the specific problem at hand or not. We know from the novels, for example, that throughout the history of wizards in England, it has been customary for all wizards and witches to be trained at Hogwarts, though not legally required, though there have been exceptions (like Arianna Dumbledore, the younger sister of Albus and Aberforth). Since Hogwarts, from the novels, has an incoming class of 40 witches and wizards per year, we can safely assume that all of the witches and wizards from England, Scotland, Ireland, and Wales are among those 40 per year. If we assume that the average witch or wizard lives 80-100 years, that would give approximately 3200-4000 wizards for the entire British Isles. This is not a very large proportion at all.
We do not know the maximum number of witches and wizards per year, but if it is 40, and has been 40 since the beginning of Hogwarts, it would mean that there is a fixed amount of magic that must find its way into a newborn or young child in the world, and that if existing magic using families have an insufficient number of children that muggles will receive the blessing of magic. Additionally, if magic-using families are too prolific in having children, then the result of “excess” children or families that are too inbred would be squibs. The record we have of squibs in the HP universe (Mr. Filtch and Mrs. Figg) suggests that squibs are far less likely to marry and have children than the normal population or normal wizard population, presumably due to being highly undesirable marriage partners either under the “pure blood” or “blood traitor” strategy of mating and due to their lack of knowledge with the muggle world and inability to find normal muggle marriage partners.
It may be, given the size of Hogwarts grounds, that there is the room for more students than currently go there, but that no less than 40 students will enter from each incoming class. The existence of squibs means, though, that there is an absolute maximum of incoming students as well, by birth year. It is possible that 40 students in each class at Hogwarts may be the absolute maximum as well. Therefore, given these assumptions, if the total number of magic families in existence have more than 40 children in a given calendar year (September 1 to the next August 31), those excess children will be squibs. Likewise, each vacancy among the children of existing magic-using families will lead to the presence of a new muggle witch or wizard.
The Implications On Population Dynamics
These assumptions would lead to serious implications on the strategy of a wizard family to gain and seize control of the Wizanganot. It is unclear just how many wizards and witches are members of the Wizanganot, but the answer appears to be at least two or three hundred. It could be as much as 10% of the entire wizard population, or maybe even a little more than a tenth of the adult population of wizards. There is no known way of determining who is in the Wizanganot, whether it is an elected or appointed or inherited position. Nonetheless, it would appear that the Ministry of Magic itself is an elected position (though the vagaries of wizard suffrage are not sufficiently clear within the Harry Potter novels to understand how this parliamentary democracy of wizards works). Given the low number of wizards, it is unclear just what means provides the leaders among the wizard population in Great Britain (to say nothing of other countries about whom we know even less given the point of view of the series).
Let us take the size of an incoming class at Hogwarts as a rough estimate of one’s dominance within the wizarding population at large. A family or alliance that was able to ensure about 20 children a year in the wizard population would have control of the wizard population by mere demography. Even a fairly consistent adding of 3-5 witches each year in a given generation, if those generations also had plenty of children, could then lead to fairly extensive gains in control over the course of several generations. Likewise, a “pure-blood” strategy would require that pure blood houses out-breed blood traitor houses in order to maintain their position within the wizard population.
A Tale of Two Strategies
Let us therefore compare two strategies to gaining power and influence within the wizard community. These are “pure” strategies, and though other options exist, these represent the purest contrast possible. Strategy A is the “pure-blood strategy,” which would require each member of such a family (like the Malfoy family) to find a pure blood partner and then raise children. Strategy B is the “blood traitor strategy” which would encourage children of such a family (notably the Weasleys) to marry the most notable and ambitious wizards of non-pure lines that they can find (see: Harry Potter, Hermoine Granger, and Fleur Delacrour), even across international borders.
A pure blood strategy could succeed, assuming that excessive inbreeding does not lead to squibs and assuming that one could have children above the rate of replacement (2 children for each set of parents) in order to prevent the necessity of muggle children being born with magical abilities given the apparent 40-wizard live births per year Hogwarts requirement. Most of the pure blood families have fallen asleep on the job. In 19 Years Later, the epilogue to DH, we find that Draco Malfoy, the only child of two pure-blood wizards, only has one child, Scorpio, from his pure-blood marriage (to the former Miss Daphne Greengrass). Thus four pure-blood grandparents lead to only one pure-blood grandchild. This sort of diminishing of numbers means that 3 extra Hogwarts places have been taken up by muggles and half-bloods than would have been the case had each generation had an extra child.
Likewise, the First and Second Voldemort Wars caused grave problems in the number of pure blood families. Far from making the position of the threatened pure blood wizard families secure, it made it more untenable. For example, Neville Longbottom is a pure blood wizard, but his parents were unable to have any more children because Bellatrix Lestrange drove them both out of their minds with the Cruciatus Curse. Bellatrix, though married to a fellow named Rudlofo, does not appear to have had any children of her own, and therefore two pure-blood wizards failed to produce any children in the next generation. While Voldemort is at least clever enough to realize that spilling pure blood is a bad strategy (which accounts for Neville’s survival during a ghastly 7th year at Hogwarts), he apparently is not a student of population genetics, and thus his inattention to the magic of love (including the need for children to follow to continue one’s family legacy) means that his “culling” of the magic population has led to far more muggle witches and wizards and half-bloods simply because of the lack of alternatives. That said, a great deal of other wizards (including Dumbledore) appear equally ignorant of the importance of population genetics in the wizard world, as the Dumbledore family managed the rare (and unpleasant) trick of having three children, none of whom apparently married or had children. Arianna died young, Aberforth was interested in goat-charming rather than girl-charming, and Albus was himself a homosexual. This is how wizard family lines get extinguished. A similar story could be told for the extinguishing of the Gaunt family line (neither Morfin nor Voldemort had any children, after all).
So, in the absence of a successful pure-blood strategy, it would appear that the Weasley strategy is highly successful. Again, let us look at three generations of the Weasley family to see how their strategy could easily lead to a gain in power and influence through the generations. We know that Arthur and Molly are not the only Weasleys, for we hear about “Weasley cousins” whose red hair is easily recognizable and a trademark to others. Arthur and Molly, of apparently pure-blood ancestry, had seven children (Charlie, Bill, Percy, Fred, George, Ron, and Ginny). Fred died in DH. Bill married Fleur Delacreur (a French witch), and had three children (Victorie, Dominique, and Louis). George married Angelica Johnson and had two children (Fred II and Roxane). Harry Potter and Ginny married and had three kids (James II, Albus, and Lily), and Ron and Hermoine married and had two children (Rose & Hugo). Percy married and had two children as well (Molly II and Lucy), and he was stated as being at the platform in the “19 years later” epilogue of Deathly Hallows. Therefore, we can calculate that the Weasleys have a total of twelve grandchildren, out of seven children, a healthy rate of growth.
Nor does it appear likely that this is the end of the Weasley strategy. Victoire is caught snogging a family friend and foster-child, Teddy Lupin, and given the Weasley’s charms, it is likely that he will soon enter the “House of Weasley” himself as soon as she is of age. This would continue the Weasley family tradition of marrying particularly skilled or ambitous wizards and witches. How might this strategy be seen as successful? For example, we see that the Weasleys (and their allied families like the Potters) have at one time about twelve members of the Gryffindor house (which has a maximum of 70 students). Therefore, it would appear that the Weasleys could have almost 20% of that house’s entire spots, and as much as 5% of the entire population of Hogwarts. That’s a fair amount of power and influence for one single family within the wizarding world of England, and a testament to the declining number of wizarding families due to the failure to marry and have children.
It is unclear to what extent J.K. Rowling herself has examined (or, it would perhaps be better to say determined) the limits of the magical world. For one, the fixed number of magical slots and the growing population of the Muggle world would appear to mean that the magical population is an ever-shrinking minority. Where once 4000 wizards may have been a substantial portion of the English population (especially among elites, as wizards would have been literate in ages where such education was very rare), 4000 wizards in modern Great Britain is a drop in the bucket, and dust on the scales. At this point, the International Statute of Secrecy is for the protection of a vanishing magic-using minority rather than for the good of the human population at large, whatever its original intent, simply because of the scourge of population dynamics.
Likewise, it would appear that long-term, the “houses” of Hogwarts are also untenable. The fact that the house with the strongest pure-blood tendencies (namely Slytherin) is likely to be suffering from extreme population losses on a generational level due to the failure to have children or have more than one child per family, and that houses like Gryffindor and Hufflepuff are likely to only get stronger as the proportions of muggle witches and wizards and Weasleys increases, meaning that eventually a different system of determining houses rather than the competitive sorting hat method (which fosters intergroup rivalries) will have to be chosen simply because of the skewed population of witches and wizards. The Slytherin House appears to be on the way of being bred out of existence. One wonders whether they will go with a bang, in the form of a last-ditch Wizarding war to protest the rise of the muggle-borns or the choice of a Percy Weasley or Harry Potter to run the Ministry of Magic, or whether they will go with the whimper of extinct family lines and aging pure blood families like the Malfoys bemoaning the lack of suitable marriage partners for their arrogant brats. Either way, the pure bloods will either be bled or bred out of existence. Love is indeed a powerful and deep magic.