wizard geneology - Genius or Baloney?

[kelleyaynn]

No: HPFGUIDX 148115


> bboyminn:
> 
>> Unless I'm mistaken the DNA chain splits in half length-wise, and 
half
> of your mother's combines with half of your fathers. That is all of
> your fathers 'halves' combine with all of your mother's halves, and
> the combination creates a complete DNA ladder. When two specific 
DNA
> halves mate, they create the genetic characteristic of blue eyes,
> brown eyes, prone to cancer, or whatever.
> 

Kelleyaynn:

Not quite. The DNA chain splits in half during the formation of new 
cells so it can replicate itself. The DNA has to replicate so extra 
cells have all the DNA they need. In mitotic cell division (like the 
kind that repairs wounds), the DNA must copy itself so each of the 
two daughter cells have the requisite chromosomes. In meiosis, which 
creates eggs and sperm, the DNA also replicates, since from one germ 
line cell you get four sperm (you only get one egg, but that is 
because the other three basically disintegrate). In meiosis, there 
are two cell divisions: one to half the number of chromosomes, and 
the other to split the replicated chromosomes apart (hence the four 
cell result instead of two). 

There are only twenty-two types of chromosomes in humans (plus the X 
and Y chromosomes), but we have two of each type. One of each pair 
comes from the mother, the other from the father. So in reality, we 
have two copies of every gene, and it is the combination of which 
copies we get that determines the actual result. It isn't that the 
halves come together (the DNA chain pretty much forms the new half 
right as the chain splits in half), but a pair of chromosomes is 
found in each cell (and they do not physically associate with each 
other except during cell division).

That's a simplified version. I hope it makes sense. Genetics can be 
quite complicated, though it is endlessly fascinating (at least to 
me!)


>bboyminn:

> So, if there are four magic genes they can either be active or
> dormant. Let me represent 'active' genes with CAPITAL letters and
> dormant genes with lower case letters.
> 

Kelleyaynn:

Genes are neither active nor dormant. They are dominant or 
recessive. Recessive does NOT mean that it doesn't do anything. It 
just means that when it comes to actually seeing the physical result 
of the two gene copies, you only notice the dominant result. In 
fact, for most traits, dominant and recessive is irrelevant, and 
geneticists rarely talk about dominant and recessive alleles (the 
gene copies) - what happens is usually more complicated than simple 
Mendelian genetics. 


>bboyminn:

> Now say the Father is ABcd and the mother is aBCd, the son would
> surely be, at bare minimum, aBcd. Both parents are 'B' active, that
> guarantees that the son would be 'B' active. Now however, the 
father
> is 'A' active while the Mother is 'C' active, but the Mother is 'a'
> inactive and the Father is 'c' inactive. I think those genes are
> somewhat luck of the draw. Though not necessarily mathematically
> correct, in general, the son has a 50/50 chance of either being 'A'
> active, 'C' active, or both.
> 
> So the son is guaranteed to be
> 
> aBcd
> 
> but could potentially also be any one of the following
> 
> ABcd
> aBCd
> ABCd
> 
> The comination is guaranteed to always produce 'B' active and 'd'
> inactive, and 'ac/AC' are luck of the draw.
> 
> I think a Squib is created when an 'aBcD' father marries a 'AbCd'
> mother, and by luck of the draw, the son turns out to be 'abcd', or
> all magic genes are 'inactive'. The most powerful wizard would be
> created by the combination of an 'ABCd' Father and an 'aBCD' 
mother,
> and luck of the draw produce an 'ABCD' son (or daughter). The 
minimum
> the son could be, would be 'aBCd'. 
> 
>

Kelleyaynn:

Not sure how to address this and ignore the "active" and "inactive" 
terms. There could be four genes that determine magic, with each 
gene having at least two different alleles. However, what makes 
magic and genetics tricky is that genes ONLY control the proteins 
made by a cell. I won't go into how proteins affect behavior, but 
suffice it to say, they do. However, thinking of a way that proteins 
could make one magical or not is purely wild speculation, and I 
haven't come up with anything that is satisfactory to me.  So, since 
muggles would also have to have the same genes that code for magic 
proteins, but somehow only have the recessive alleles that lead to 
proteins that do not give any magical ability. That would make 
squibs and muggles genetically identical. So squibs would really be 
muggles. But I don't think that JKR meant for squibs to actually be 
muggles, so I don't think this is an adequate explanation for squibs.


Ignoring the protein basis for magic difficulty, I'm more inclined 
to go with magic being only one gene with only two alleles (so there 
are only two types of protein - one that makes you magical and one 
that does not). And, magic is recessive. Having one magical allele 
will not produce enough protein to make you magical (something 
called haploinsufficiency in genetics). Squibs are the result of 
what I would liken to a severe learning disability - there is 
something else that interferes with magical ability, say like ADD. 


Whew! I hope this helped some.

Kelleyaynn