Mudbloods, Half-Bloods, Pure Bloods, and Genetics

[meriaugust]

No: HPFGUIDX 88701

--- In HPforGrownups at yahoogroups.com, "drjuliehoward" 
<drjuliehoward at y...> wrote:
> I have a strange question that I know has been touched upon in 
some 
> ways by past posts.  It has been 17 years since I had genetics so 
my 
> knowledge is very rusty.  How is magic passed down genetically?  
> 1.  It cannot be Dominant, given that there are squibs and 
mudbloods.
> 2.  It cannot be complete recessive, given that there are 
halfbloods.
> 3.  At what point is a wizard a pureblood?  
> 4.  Is magic genetic at all?

Meri here: 
I am no geneticist, but I don't know if it is as simple as having a 
magical gene or a magical chromosome that gives a person magical 
ability. Perhaps it is something more akin to an inheritied talent 
(like the Force in Star Wars) that manifests itself in certain 
people. And maybe having two wizards for parents merely increases 
the likelihood of magical offspring to near certaintity, but, 
because of the existence of squibs, is no guarantee that your kid 
will get an acceptance letter from Hogwarts. As to the halfbloods, 
on the other hand, they exist because witches or wizards intermarry 
and produce off-spring with Muggles or other creatures, and since 
these marriages seem to always produce a magical child (Seamus 
Finnegan, Tom Riddle, Hagrid are some examples) we can assume that 
magical ability is not a trait inherited through the normal crossing 
of chromosomes, otherwise we would have evidence of at least a few 
children of one magical/one Muggle parent who is all Muggle. (Who 
knows? Perhaps Seamus has a sister who takes after Mr. Finnegan?) As 
to your third question, being a pure-blooded wizard, IMHO, has less 
to do with the number of Muggles in your family or your opinions on 
Mudbloods (though those are some definig factors of certain 
pureblood families) and more to do with the status of your family, 
so being a pureblood versus a Mudblood could be more akin to being 
royal or noble versus common than being of a pure race versus a 
mixed racial background, at least that's my interpretation. 
Meri (who now wishes she saved her science 101 textbook for this 
discussion but needed the buy-back money)