Let's just jump right into it. When we talk about genes, we have some which are dominant, and some which are recessive. That's the simple version. For the sake of argument, we'll say that the magic ability is dominant, one parent can have a magic or non magic baby. I get that this might not be the case, but for the sake of explaining the process, just stick with me. As with every science the truth is usually much more complex. Anyway, now say that the original magic users, whoever they were, also possessed a gene for sensing magic, a recessive gene that was never expressed so passed on silently. We'd call that person a carrier, just like you would if they had a virus and didn't show the signs. When two carriers - users or magic or not - then had children together, then those hidden genes - magic sensing - might finally express itself. The amount that you're seeing it happening would make sense with that kind of model, as generations intermingle. Someone who sensed magic would only need that one gene to come down to them from both their family lines, and have a parent or great grandparent or ancestral grandparent in common with each other. As you breed for one thing - and I know we're talking about people here, but affluence does have its effect in our choice of partners - you inevitably get genes that come along for the ride, like for example spotted dogs that suffer from liver failure, or horses whose color is linked to the breed's propensity toward corneal detachment. This whole thing much easier to explain with two different colored apples, just so you know.
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Anyway, now say that the original magic users, whoever they were, also possessed a gene for sensing magic, a recessive gene that was never expressed so passed on silently. We'd call that person a carrier, just like you would if they had a virus and didn't show the signs.
When two carriers - users or magic or not - then had children together, then those hidden genes - magic sensing - might finally express itself. The amount that you're seeing it happening would make sense with that kind of model, as generations intermingle. Someone who sensed magic would only need that one gene to come down to them from both their family lines, and have a parent or great grandparent or ancestral grandparent in common with each other.
As you breed for one thing - and I know we're talking about people here, but affluence does have its effect in our choice of partners - you inevitably get genes that come along for the ride, like for example spotted dogs that suffer from liver failure, or horses whose color is linked to the breed's propensity toward corneal detachment.
This whole thing much easier to explain with two different colored apples, just so you know.