I'm betaing a Harry Potter/Stargate crossover for someone and we've been discussing the ATA gene and if it has an effect on HP magic or not/controls HP magic or not. She came up with this and asked if this was sound. From what I can understand, it seems to be, but I thought I'd get a second opinion (obviously, this is directed mostly at Trojie, goddess of biology). In case you're not familiar with Stargate, the ATA gene (does that actually stand for anything?) is what gives people the ability to control Ancient/Alteran technology.

"There are three general principles that are the basis of this theory.

1. Either you have a gene, or you don’t.

2. The expression of genes you do have can be strong, weak, something in between, or even non-existing.

3. Promoter genes are genes that tell other genes if they should be turned on or off, and how strong their expression should be.

Keeping that in mind, if you look at the ATA gene, you either have it, or you don’t. If you don’t have it, you cannot turn on, or in some cases even control, Ancient technology. If you do have the ATA gene, the expression can be different. O’Neill, Beckett and Sheppard, for instance, have a very strong expression.

The ATA gene has shown no sign of being recessive, so I’m considering it as a dominant gene. It is, however rare, and needs some promoter genes to work, which is the reason the gene therapy works for McKay, but not for everyone. McKay has the necessary promoter genes to turn the gene on, while others don’t have it, so the gene therapy doesn’t work on them. The promoter genes are passed on separately from the ATA gene, so active ATA genes are not always heritable.

All magical people, and that includes most Squibs, have the ATA gene, but in order to have working magical abilities, they need to have an additional, dominant gene, which I’ll call the MAG gene. Squibs, born from two magical parents, do have the ATA gene in most cases, but lack the MAG gene, so they can’t do magic. Muggleborns have one parent with the ATA gene, while the other has the MAG gene, and they have inherited both, enabling them to do magic while their parents can’t. The fact that Wizards need both rare genes to be magical accounts for the very low number of magical people on Earth.

Magical ability is correlated with the expression of the MAG gene, just like the strength of the ATA gene is correlated with its expression.

In my story, Daniel has both the ATA gene and the MAG gene, with a moderate ATA gene expression and a strong MAG gene expression (like Harry had before the merging). Jack doesn’t have the MAG gene, but he does have the ATA gene and it is expressed very strong."