Does ancestry play a part in magical ability? was: The permanent prob. with

[corinthum]

No: HPFGUIDX 99430

Mandy asked:

> The question is then; does ancestry play a part in the magical 
> ability of children? 

...

> Do the children of two Magical parents have an advantage? If they do 
> then selection based on blood purity has validity and merit. They 
> would by nature have greater potential to pass on to their offspring, 
> and the rules of natural selection dictates that at least some 
> pureblood must remain or the WW would eventually die out.


This would only be true if magic behaved as a genetic trait, which
previous discussions have led me to believe it does not.  Pureblood
and half-blood are only social terms; they don't seem to have any
basis in fact.  

First of all, the magic ability does not come in degrees; you are
either a witch/wizard, or you aren't.  The terms pureblood,
half-blood, and Muggle-born don't actually indicate anything about
level of ability.  I don't think Rowling could possibly emphasize this
point any more than she has; she's given us Muggle-borns with above
average ability (Hermione, Lily), purebloods with below average
ability (Neville, Crabb, Goyle), and the entire spectrum in between. 
The lack of a correlation between magicness and number of magical
parents indicates against magic being a multi-gene trait.  

Also, magic ability is certainly not inherited as a single-allele
trait.  From what we've seen, a muggle-born with is as likely as a
pureblood to have magical children, i.e. extremely likely.  Ohterwise,
I would have expected to hear about this phenomenon when we were
introduced to Squibs, who despite numerous theories remain an extreme
minority.  I disagree with the idea that purebloods must remain or
magic will die out.  It seems that once magic "appears" in a child,
it's available to be passed down to future generations, regardless of
how that child received it (whether from two magical parents, only
one, or by the random chance by which it appears in Muggle-borns). 
And in a similar line of thought, "inbreeding" between purebloods
shouldn't have any negative effects on the magical ability of their
children (although the normal genetic results will of course surface
if it continues in too small a group).

So, in my opinion, no, purity of blood remains a social idea, and does
not convey any actual benefit, other than social acceptance in certain
circles.  

-Corinth