[HPforGrownups] Re: Wizards, Muggles, and Genetics (long)

[charme]

No: HPFGUIDX 119735

>>
> Maddy replied:
>
<snip>
<snipping the biospeak>

> With that I would think that Squibs would be a bit more
> common...and how do muggles with "mm" recessive magic genes
> spontaneously produce "Mm" or "MM" magic children?
>
> Unless it's possible to carry the magic gene, but not be dominant,
> then I can't figure out how it would happen. Are there any other
> biologists here with better knowledge of genetics to shed some
> light on this?

charme responds:

This is so cool!!! I didn't know how my post would be rec'd and I'm jazzed 
that people are asking the same questions I am.  The one other question I 
have is if in Muggles magic is the RECESSIVE gene, and non magic is the 
DOMINATE one (the opposite of what wizards are supposed to have), and what a 
fine kettle of potion that would be to figure out....


Dungrollin:

<snip>
I agree that the magic gene must be recessive and the non-magic gene
dominant, otherwise at least one of Lily and Petunia's parents
would have been a witch or a wizard.

<snip>

If the two copies are the same - e.g. Muggle/Muggle, then
you're a Muggle, similarly if they're magic/magic, then
you're a witch or a wizard. If they're different, then (aside
from complications like co-dominance that I won't get into) one
geneis expressed and the other is not, so it depends on which gene is
dominant. If the magic gene is dominant, then magic/Muggle people
would be witches or wizards, if the Muggle gene is dominant then
they'd be Muggles or squibs.

So if the magic gene is dominant, then for Lily to have been a
witch, at least one of her parents must have had at least one copy
of the magic gene.  That would make one of her parents magic/muggle
or magic/magic - ie, a witch or a wizard.  Geddit?)

charme responds:

Yep, I geddit. While I used the analogy of blood type to make my point, I 
could have complicated it more by using eye color genetics which is far more 
complex. For example, for a child to be born with blue eyes, it means both 
genes with all 4 alleles (alleles are variations of genes and for this 
illustration, 2 alleles to a gene) for eye color must be all blue as blue is 
a completely recessive trait. Brown swamps blue, and green will swamp blue 
too, however it's not all so simple as that, since their other variations in 
the 4 alleles which produce hazel and other multi shaded eye colors (lending 
to your comment about co-dominance.)

<snip>

But...
If Squibs are just muggles brought up in a magical household, how
can they see dementors? (Thinking of Mrs. Figg's insistence in
the court.)  If there's no difference in the magical ability of
purebloods and Muggle-borns, being brought up in a magical
atmosphere can't make that much of a difference, can it?

charme responds:

Per JKR's own website admittance, Arabella didn't see the Dementors but knew 
enough about the conditions and symptoms to know what the boys were 
experiencing.  :) And I submit we are products of our environment in the 
Squib/Muggle comparison:  Squib's aren't magical people, they have just been 
raised in the magical environment and know what to expect.

Although there's the idea of magic genes acting as segregation
distorters... Or the magic gene being mitochondrial, so only passed
through the female line... Jumping magic genes... Not to mention,
what exactly is the product of the magical gene? (If it is indeed
only one gene.)  Magical proteins?  Magical hormones? Oh the
possibilities are endless...  I somehow doubt that JKR has gone into
too much detail.

What I'd like to know is what you call the non-magic offspring of
a witch/wizard and a Muggle.  Are they Squibs, or Muggles?

charme, finally:

Oh this is such a great question! :) It's also exemplifies exactly what I 
was theorizing about Squibs and Muggles:  are they *really* that 
different???