Squibs have genes to do magic?

[tylerswaxlion]

No: HPFGUIDX 146476

--- In HPforGrownups at yahoogroups.com, Bart Lidofsky <bartl at s...> 
wrote:

Steve wrote:
 So, let's ask ourselves from a more practical stand point if it is 
possible for a genius or a retarded person to occur in a family of 
people with normal intelligence? It would seem that both these 
events do occur.

Tyler:  In the same family, even.

Bart: (slightly paraphrased for length)
Consider, one magic gene pair, [recessive]. We will call the magic 
version W for Wizard/witch, and the non-magic M for muggle. [snip] 
ALL wizards would be WW, but unless a wizard marries a WM muggle 
(WM's would not be magical), all the children would be squibs. On 
the other hand, if a WM muggle marries another WM muggle, one out of 
4 children would be magical.

Tyler:

I don't think a single gene solves it.  You need at least two.

Magical ability seems to come in degrees, not simply a yes/no 
choice.  It's not like gender--you're either a boy or a girl.  You 
can get a Filch or a Dumbledore or a Fudge.   Some of it is 
training, but not everyone can master the basic spells to qualify 
for the training.

I think it's more likely that magical ability is related to multiple 
genes, probably on multiple chromosomes.  Like some rare diseases--
it's not enough for each parent to have one recessive gene, but they 
each have to have multiple recessives.  

Wizarding families intermarrying would be a bit like blue-eyed 
people--everyone has the recessive magic gene, so everyone is 
predisposed toward a magical ability.  But depending on whether or 
not the second gene is also present, let's call it a power gene, the 
strength of the magic is affected.  

You need a bigger grid  for the W-wizard, M-muggle genes and the P-
powerful, S-squib genes, so I'll just use subsets for simplicity.

Suppose two wizards with double recessive wizarding genes marry, 
each having one dominant and one recessive power gene.  you get
Parents:  WW/PS + WW/PS =
          WW/PP WW/PS
          WW/PS WW/SS

Where one in four is an extremely powerful wizard, two are ordinary 
wizards and one is a Squib.  Again, the odds are 1 in four will be a 
Squib, but those odds are for *each* child, so it's possible that no 
Squibs could be born or many could, depending on how many children 
this set of parents have.  

This could actually be the answer to what the real difference is 
between a Muggle and a Squib.  In a Muggle, the power gene would be 
completely irrelevant--Muggles don't have the Wizarding gene that 
allows them to use magic at all.  Squibs, on the other hand, would 
have the Wizarding Gene, but they don't have the Power gene, so they 
can't use their magical ability to any noticable degree.  Squibs 
could still produce wizard offspring if they marry other wizards.

Squib--WWSS  Wizard--WWPS  or Squib--WWSS + Wizard--WWPP
       WWSP WWSS                     WWSP  WWSP  
       WWSS WWSS                     WWSP  WWSP

where the first is a Squib with an ordinary powered wizard having a 
1 in 4 chance of a wizard child and the second a Squib with a 
powerful wizard having all ordinary powered wizard children.

Squibs marrying Squibs in this scenario would produce all Squibs.  
Who might then move into the Muggle community, perhaps marrying 
Muggles with the power gene.  Eventually, their descendents might 
pop up as wizards.

Additionally, statistics don't always "show" with small samples.  I 
have brown eyes (dominant) and a recessive blue gene.  My spouse has 
blue eyes.  My kids had a 50/50 shot at my brown eyes, 
and "statistically" one of the two "should" have had brown eyes.  
However, they are both blue-eyed.  If we had dozens and dozens of 
kids, the 50/50 statistic would appear, but 2 is too small of a 
sample.  

OK, with that I'll bring this long post to a close and go to bed.  
Hope it was clear.