[HPforGrownups] Genetics and Wizarding Ablilty; was Wizard Contraception

[Firebolt]

No: HPFGUIDX 407

<It could be some form of heterozygote advantage.  <Anthropologist Lori
rears her ugly head>  This is the mechanism by which genes are passed down
through populations where certain conditions (like malaria) are indemnic
(everyone gets them)...only the heterozygotes survive and thus both forms
of the gene are passed down.>

Right. Hybrids (aka heterozygotes) generally survive better, that's known. I'm sure everyone here has heard all about how a lot of purebred dogs have inbreeding problems, like German Shepherds with hip problems, bulldogs (and Chihuahuas) who can't give birth without a C-section because the fetus' heads (or mother's hips) make it impossible for them to get through the birth canal...btw, I think you mean endemic, not indemnic.

<If the magical gene, call it M, is dominant, then both heterozygote (mM)
and the homozygote (MM) would be wizards.  It then becomes a question of
wizards seeming to prefer to associate with other wizards and being more
likely to marry and have kids with them, thus funneling all M-carrying
people into one population and removing then from the other.>

Which is inbreeding, of course. Plus Muggleborns would be impossible, as you've already stated.

<But I think any magical gene would have to be recessive.  If it weren't, it
would be impossible to get a magical child from two Muggle parents.  If M
is recessive, then both parents could be mM and still be Muggles, but their
child would have a 1-in-4 chance of being MM and therefore a wizard, a
1-in-2 chance of being mM and a carrier themselves, or a 1-in-4 chance of
being mm and neither a wizard nor a carrier.>

And of course, since with every child the roulette wheel starts spinning again, it's perfectly plausible to have Muggles families like the Creeveys where more than one child is magic. 

<Since everyone in the
wizarding world would have to be MM, then they'd have all magical children.
This does not explain how wizards could have non-magical children, though.
It ought to be impossible if magic is recessive...however, almost no
traits are coded for by a single gene.>

*Extreme sarcasm* Except in Muggle high school textbooks, where there are only two eye colors, brown and blue, and Punnett Squares using two different traits are 'difficult'.  Thank goodness my bio teacher said we'd be covering linked genes, or I'd go positively mad.

~Firebolt


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