Percentage

[Maple_and_PheonixFeather]

Did Rowling say that it was recessive? I honestly don't see how that works, as then there'd be no muggleborns and no halfbloods, you know, wizard and muggle children...I don't know...

[lucca4]

Oh, back to this classic debate again. Believe it or not, there have been several very long threads devoted to discussing whether or not the gene for magic is dominant or recessive. We really don't see enough large families created from mixed couples to know for sure.

I think being magical is just something you inherit that genes have no effect on (like Downs Syndrome, for instance). Because it gets contradictory once you label it "recessive" or "dominant."

If the trait was recessive, Squibs would be nonexistent because it wouldn't be possible for a witch and wizard to carry a Muggle gene. If the trait was dominant, Muggleborns wouldn't be around, as there would be no way for a Muggle parent to transfer a wizard gene to its child.

Onto answering your question: I don't think any Muggles are allowed to know of the existence of witches/wizards. News travels fast around the world, and it's impossible to trust everyone to be discreet.

[OliveOil_Med]

This might not really be a credible sorce, but on Harry Potter Wiki, I found an article saying that the magic gene is dominant. But then, I would welcome the introduction of other articles and what they say about wizarding genetics.

And there is an excellent essay on the Lexicon about genetics.

http://www.hp-lexicon.org/essays/essay-magic-genes-and-pure-blood.html

[emck]

I'm studing genetics atm (I just watched ten hours of lectures online in two days studying for an exam), so even though I can't be bothered to write an essay about wizarding genetics, I do have a bit of a theory

Okay, so first off, I'm not sure that there'd be one single gene for magic - that doesn't take into account the differences in magical abilities and things - I think it's probably a sequence of genes that work together. The genes for magic are probably a mutations of a genes, i.e. a phenotypes. Genes/gene sequences can be turned on and off by enzymes (or something, I didn't fully understand this part), right? So I kind of think that the wizarding gene would be dominant, i.e. loads of people have it, but only some people actually express the gene (and you only have magic if you're able to express the gene, and it requires a special enzyme or amino acid, or someting)? That probably doesn't make sense at all, but yeah