[part 2]
which, comes to my next fascination: the Squibs. i feel like if Squibs are that rare, the wizardsâ population should grow a lot more? if anything, i think Squibs birth rate should be about equal to that of Muggleborn wizards. i mean, sure, wizards were persecuted throughout history and thereâs the wars and conflicts, hence them being minority. my theory is that it was actually the Purebloods who produced Squib births the most (compared to Halfbloods and Muggleborns) as another side effect of inbreeding, which would be ironic: their attempt to maintain their blood purity totally blew up in their faces. i also like to think famous Muggles were really Squibs or directly descended from them; they may not be magical enough to use the magic around them, but have enough in them to stand out among the non-magic folks.
oh my this has gotten way too long
P.S.: you once dubbed me as âthe Fantastic Anonâ as i sent multiple asks about the FB series lol (just so you can make the connectionsâif thereâs one to be made)
It's so good to hear from you again! I believe that first question was answered on Pottermore. Actually, I think a couple of these questions were answered. Typically, the family of a muggle-born is presumed to be trustworthy with the secret of their child's powers. And the fallback plan if someone does go rogue and blab about the wizarding world is to call the bluff. Like, who would believe them anyway? They'd get chucked into an asylum, especially prior to the twenty-first century. As far as squibs go, I think the answer given to why muggle-borns are common and squibs are rare, is simply that magic is a dominant gene. If the gene is present in your biological history, there's a better chance than not that it will surface in your makeup.
I love your ideas though, and I think that's actually true. True, the only squibs we know of, Figg and Filch, don't come from big name families...but hey, at least in the case of "Mrs" Figg, that's presumably her married name. We don't know her maiden name. Most of the time squibs are mentioned, it is indeed in reference to the "shame" that their (often pureblood) family underwent for having produced one. Kind of reminds me of how many special needs/disabilities are categorized not by how the symptoms affect the person but by how these symptoms cause the person to be a problem for others in society. I think that would make a lot of sense, especially since (and I'm not a biologist but I'm pretty sure) one of the side effects of stacked inbreeding is that recessive genes are more likely to crop up. I'm also living for your idea about famous muggles. Apparently, all muggle-borns have a squib ancestor. Which itself, I find a little odd. Like, that's a chicken and the egg scenario then. Where does magic originate? Were the first humans ever to walk the earth, actually magical? If not, then the first magical human born was, by default, a muggle-born, right?
OK. Â Biochemist (biologist enough for this) here. Â I love the idea of inbreeding among purebloods contributing to the number of squibs coming out of those families. Â It absolutely lines up with rare genetic disorders being a real problem for royal families (first example that comes to mind is hemophilia, which was pretty big in the British monarchy and spread to other royal families in Germany, Russia, and Spain). Â But, if magic is truly the result of a singular dominant gene (which Iâll call gene M), thereâs no way that muggleborns can exist - or, if they do, it would be a result of a spontaneous mutation that would likely occur no more than once every couple of generations. Â
In this scenario, depending on the prevalence of the recessive non-magical gene (which Iâll call gene m), the majority of squibs should actually come from half-blood families. Â Assuming that the wizard has two copies of gene M (and knowing that the muggle can only have two copies of gene m), all of their children should have one of each; thatâs fine - theyâll all still be wizards. Â However, what happens when that generation has children of their own, either with another half-blood or with another muggle? Â About 25% of half-blood/half-blood children should be squibs. Â 50% of half-blood/muggle children should be squibs. Â I guess the only kid from two half-blood parents that we ever see in the books is Teddy Lupin, but I never got the feeling that his not being magical was even on their radar.
Thatâs not to say that having magic canât be a dominant trait.  Lots of traits are polygenic (meaning that they can be influenced by multiple genes working together).  Think the almost infinite shades of human skin rather than a flower being purple or white.  Say there are 10 genes that determine whether you have magic or not, and you need to have 6 dominant genes in order to be considered a âwizard.â  It doesnât matter which 6, but you need to have at least that many.  That leaves a lot more room for non-magical m genes to accumulate in pureblood families over time.  Then you get 2 people with m genes inbred into the same 5-6 positions, and youâve got yourself a squib.  A rare occurrence because all 5 recessive genes would have to pass from both parents (roughly 1/1000 chance, assuming that the genes are passed down independently). Â
This also opens up the possibility for muggle-borns to be descended from distant squib relatives. Â Say one side of your family is descended from a squib with 4 M genes. Â They go through a few generations and reintegrate into muggle society. Â Your parent has, by chance, held on to those 4 M genes. Â Same with the other side of your family, except that squib carried the a different set of 4 M genes. Â By chance, these two muggles meet and pass on 6 of those 8 potential M genes. Â Youâve got yourself what appears to be a muggle-born. Â And while this is still only a 1/1000 chance at most (not even considering the probability of two muggles with complementary M genes meeting and having kids), the muggle population is much larger than the wizard population (meaning that muggle-born children appear more common than squib children, simply because there are exponentially more chances for them to occur). Â
And, if inherent magical ability is more of a spectrum than just a binary yes/no, it might shed some light on why purebloods try to prevent muggle-borns from studying magic.  Not because they view them as weak, but because theyâre a potential threat.  Pureblood families keep getting more and more inbred every generation, to the point where they only carry 6-7 M genes, enough to consistently have average wizard children.  Depending on the makeup of a muggle-bornâs lineage, they have the potential to carry all 10.  Not to say that the difference canât be made up with hard work and practice, but the potential that a muggle-born could be inherently more powerful than your child would be terrifying to them. I mean, itâs hard to ignore the fact that Lily and Hermione were both arguably the most gifted students in their year.
