Credit to Henry Haddock
By V. Goyne and T. de Barbarac
The term “pure-blood” is bandied about despite the decades between ourselves and the second wizarding war; a war so steeped in pureblood supremacy that witches and wizards questioned each other or defended each other and there was no inbetween.
But really, the term “Muggle-born” – how true is that word in its meaning?
The definition of a Muggle-born is someone with no magical parentage, therefore their father and mother are both Muggles.
To begin my explanation of why I do not believe that the idea of a Muggle-born having no wizarding ancestry I must first explain some Muggle science – bear with me.
I won’t go into too great detail about DNA and karyotypes and the like because I’m afraid I would bore you and I would likely not make a lick of sense. So, in the simplest of terms, I have blue eyes. My daddy has brown eyes and my mummy has green eyes. If my mummy and daddy have different colour eyes, where did my blue eyes come from? WELL!!
There are certain things that make you up to be the person you are called ‘genes’.
You get genes from your parents and that’s what makes you who you are. Different versions of the same genes are called alleles.
The brown eyed allele (B) is dominant over blue (b) and green (G), green (G) is dominant over blue (b). And we have two sets of each. Does this all make sense so far?
BB bb = Brown
BB Gb = Brown
BB GG = Brown
Bb bb = Brown
Bb Gb = Brown
Gb GG = Brown
bb GG = Green
bb Gb = Green
bb bb = Blue
So, you ask, how did I get blue eyes?
Let’s say my daddy’s genes are BB bb (Brown eyes)
And my mummy’s are bb GG (green eyes)
(This may get confusing) When a mummy and daddy love each other very much and have a baby their genetics are passed on, two from each. We can illustrate this with a table called a Punnett square:
| BB | Bb | bB | bb | |
| bb | BB bbbrown | Bb bbbrown | Bb bbbrown | bb bbblue |
| GG | BB GGbrown | Bb GGbrown | Bb GGbrown | bb GGgreen |
| Gb | BB Gbbrown | Bb Gbbrown | bB Gbbrown | bb Gbgreen |
| bG | BB bGbrown | Bb bGbrown | bB bGbrown | bb bGgreen |
There was a 1/16 chance I would have blue eyes and my daddy tells me how special I am that my eyes are the colour of cornflowers!
On to “Muggle”-borns.
A squib is someone born of a magical family with no magic. A rare occurrence in the wizarding world and more often than not they live as Muggles as it was often seen to be cruel to make them live in the wizarding world and not being able to. “I know all about squibs,” you’re thinking. “Why are you defining squibs?”
Well, the theory goes that all “Muggle”-born witches and wizards are descended from a squib. The genetics of it is rather complex but theoretically the magical allele is actually recessive.
So those who are “pureblood” would have (ww) and Muggle-borns would have (WW). W is the Muggle allele, w is the magic allele.
In the case of wizards, they will always be homozygous (the same alleles) recessive (w) and therefore magic. How they get that depends on parentage.
The child of two wizards will be ww because both parents can only pass on a w allele. The child of two Muggles is where it gets interesting.
As the non-magic allele is W (and therefore dominant), a Muggle can be the carrier of a w gene and not know it (Ww). They only time they will know is if they procreate with another Muggle carrying that allele. Ergo the parents will be heterozygous (different alleles), with the dominant allele (non-magic) being expressed.
But every cell in their body carries one chromosome with the dominant allele and one with the recessive. When the cells divide in normal meiosis (cell production – the kind that’s free of any weird mutations and errors), one chromosome goes in one of the new cells and one into the other.
Thus, when two Muggles who carry the w allele reproduce, there are three possible ways for the sex cells to combine: WW, Ww, and ww.
Expressed as the Punnett square, that’s:
| W | w | |
| W | WW | Ww |
| w | Ww | ww |
So, theoretically a large proportion of the Muggle population are carriers.
Squibs are the result of something called epistasis; put as simply as possible it means that the wizard gene can’t do anything without the Squib/Non-Squib gene being correct. Like with the W and w alleles, Non-Squib is B and Squib is b
When anything in-breeds (cats, dogs, wizards etc), you get more recessive (lowercase) expression because you’re trying to keep the recessive traits you want. That’s why pugs are so messed-up, for example, their entire genetic pool (for roughly 10,000 pedigree dogs surveyed in the UK) stems from about 50 individuals. They’re the most inbred dog breed in the world.
Pure-bloods want to keep the w allele hanging around so they marry cousins and second cousins and so on. Now while this does do a great job of keeping the magic gene in, it also has the unfortunate tendency to make it more likely for the recessive Squib gene to hang about too.
Because of epistasis, the ww genotype cannot be expressed unless there’s a B (Non-Squib) allele kicking about; the minute there’s only b alleles, you have a Squib, regardless of their ww genotype. Incidentally, the B or b thing only matters if the magic genotype is ww.
“But, couldn’t purebloods help diversify their gene pool by finding groups of purebloods from other places? Like, there’s only a few families left in Britain, but this says nothing about the rest of the world. If British purebloods married foreign families, they’d help their own cause.”
Well that’s the funny thing. Britain’s pretty much the only country that gives a monkey’s about blood purity. The rest of the world goes “you’re hot” and gets on with it!
Pure-bloods basically just want to be the pugs of the wizarding world.