Mudbloods, Half-Bloods, Pure Bloods, and Genetics

[cowjock13]

No: HPFGUIDX 88821

Julie wrote:
> 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?

I am actually a half-way geneticist (no, really!), and couldn't 
resist de-cloaking for this one (Geek alert!).  

It's likely not a simple Mendelian characteristic.  A multi-loci 
operon would function nicely to give the "shades" of intermediate 
power ranging from non-existent (muggle) to extraordinarily powerful 
(full wiz).  Very similar to what we are seeing from the human 
genome project as to familial susceptibility to cancer and other 
diseases.

Since it appears to run in some families and "pop up" in others, it 
would appear to be genetic, or as much as we can tell from the 
limited anecdotal evidence JKR has presented thus far.