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

[Juli]

No: HPFGUIDX 119750


> Maddy wrote:

> If we let "M" and "m" represent the alleles for
> magic (M) and
> non-magic (m), with "M" being dominant and "m" being
> recessive...
> 
> mm = the genotype of a muggle or a squib
> Mm, MM = the genotype of a witch or wizard
> 
> mm X mm = mm (Two muggles or squibs will only end up
> producing
> non-magic children)
> 
> Where as:
> Mm x MM = Mm, MM
> MM x MM = MM
> Mm x Mm = MM, Mm, mm
> (Witches and wizards almost always produce magical
> children.)
> 
> 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?
> 
Juli: 
I'm not much of a genetist either but I do know a
little about the genetics of disease. Let's say
Wizardness is a disease just like Parkison's,
Alzheimer or Diabetes. All this deseases and many more
have something in common: they are all inherited, but
not every generation needs to show or manifest the
disease, they are what's call Poligenic diseases,
which means several factors combine to get the
disease. 

Now back to Wizards: wizards seem to have a dominant
gene (M im Maddy's exemple) which means it will always
show itself (all kids will be wizards), but if both
parents have a rececive gene (m), there's a 25% chance
that the childrens are born Squibs.

Muggle borns are much more complicated: since neither
parent must have the M gene (this would mean either
parent is a wizard), there must be some spontanous
mutation, just like Darwin showed us (remember the
theory of evolution). Or in muggles families the
wizarding gene could act as a recesive allele,
therefore two parents both with the rececive gene (m)
for wizards have a 25% chance of a wizard ofspring.
But most likely it acts as a poligenic inheritance (as
mentioned above) where several factores (the
enviroment, genetics, culture...) combine for the
wizardness to show itself.

Juli, hoping this will be easy to understand