Magic Genetics

[mongo62aa]

No: HPFGUIDX 31809

--- In HPforGrownups at y..., "milztoday" <absinthe at m...> wrote:
> Magical genetics has been discussed in the Group several times. 
These 
> discussions are based on the following assumptions 1. that the 
Magic 
> Gene (MG) is unique to Magicals  and 2. that the MG inheritance can 
> be reasonably explained by simple Mendelian Genetic models. 
However, 
> these assumptions do not satisfactorily explain the existence of 
> Squibs within Magical families nor the existence of  'de novo' 
> Magicals in Muggle families (Muggle-borns) because of the heavy 
> reliance upon random point mutations and gene translocations.I 
would like to add some thoughts about this idea.
 
We have three facts that we need to explain:

ONE: Babies with magical potential can be born to non-magicals. At a 
guess, 1-10 first-year 'Mudblood' students enter Hogwarts each year. 
There are roughly one million babies born each year in Great Britain, 
so the ratio is between 1 in 100000 births and 1 in 1000000 births.

TWO: 'Squibs' are also born to magical families. Argus Filch is one, 
and Nevill Longbottom is almost one. Given the much smaller magical 
population of Great Brittain, this must be a much more frequent 
event, say 1 in 100 births.

THREE: Marriages between magical and non-magical people produce  
magical children at least some of the time.

The simplest explanation for this would be that there are at least 
two recessive genes involved. The first gene has a frequency of 
0.1%, and stimulates magic. The second gene has a frequency of 10%, 
and inhibits magic.

With these percentages, we would expect that children of two magical 
parents would be magical 99% of the time, and non-magical 1% of the 
time.

The children of one magical parent and one non-magical parent would 
be magical 0.2% of the time, and non-magical 99.8% of the time.

The children of two non-magical parents would be magical 0.0001% of 
the time, or 1 in 1000000 times, and the rest of the time be non-
magical.

William