A genética pode explicar as várias habilidades mágicas?

Este post foi citado um webchat com JKR :

How can two Muggles have a kid with magical powers? [...]

A. It's the same as two black-haired people producing a redheaded child. Sometimes these things just happen, and no one really knows why! [...]

para o qual eu comentado

Even a brief glance at Wikipedia already explains that Red hair is a recessive trait, i.e. a single ginger somewhere far up in each parent's ancestry is enough to chance this. Is JKR seriously not aware of genetics? Now that she compares it, magical abilities might as well be a genetic trait, albeit more complicated what with Squibs...

ao qual xDaizu emendado:

...not necessarily more complicated than redheadedness. I mean, just like blood type, it could be a single gene deciding if they produce magic midiclorians or not :)

Então, qual é a analogia apropriada ao sistema do tipo sanguíneo AB0 para explicar os Wizards / Witches, Squibs e Muggles?

Um problema que estou tendo em dar uma explicação é a discrepância entre a afirmação de JKR

"Muggle-borns will have a witch or wizard somewhere on their family tree, in some cases many, many generations back. The gene resurfaces in some unexpected places."

que sugere que a magia é simplesmente um traço recessivo, versus a afirmação

A Squib is a non-magical person born to at least one magical parent.

que sugere que os pais trouxas de bruxos / bruxas são na verdade Squib (-descendente) s.