Threefold (help I accidentally a setting)

[Kappa]

Thoughts had on the bus:

So I said that magic runs in families somewhat, but isn't literally genetic, and that identical twins always have the same mage status. Well, I've figured out how that works!

When a person is conceived, the magic looks at their genetic resemblance to past mages, finds the mage they are most closely related to, and the degree of that resemblance is the new person's chance of getting mage potential. (So identical twins, who are made from a single conception, are either all mages or all not mages depending on how the metaphorical dice came out originally.)

If you have no genetic resemblance to any past mages, such as because there aren't any, then your chance of becoming a mage is tiny but not literally zero, so that's how the system got started. And I think if you're a clone of a mage, your chance of becoming a mage is high but not literally 100%.

I am very proud of my clever idea.

[Unbitwise]

Does a Light mage suffer from being a double agent / I Was Only Pretending To Be Your Friend? (Other than by having less time to maintain their real relationships.)

[Moriwen]

Jean is still complaining that none of these fit him.

Earth: he's not just terrible at self-knowledge, he's actively disinterested in having a coherent "self," his whole deal is being whoever he needs to be.
Air: he is definitely not interested in the world; he's all about more abstract spheres, aesthetics and impressions and the way people relate to each other.
Light: he does not people at all. He manages to have one or two genuine relationships in his entire life. Betraying people is his MO.

I'm not sure I can even come up with one of these that's less wrong for him than the others. He's inclined to sit off in a corner and grumble that there isn't an element about aesthetics. :P

[Eva]

Let me see, sorting hat time.

Eva: Hands-down Air, not even a question.
Realist: Also Air, but for really different reasons. Wishes he was Fire: is Air anyway.
Lioncourt: Insists she's Earth. Terrible at basic geomancy. Mysteriously a really good surgeon.
Kumi: Pretty precariously balanced, but slides into Light. Depending on the instance, might be Fire or Wood.
Jinx: Water. Feels ripped off by not being an immortal godmage.
Soph: Light. Absolutely Light. Sometimes getting her ass kicked by the drawback, but Light.

[Kappa]

Light mages might indeed suffer from maintaining false friendships.

Eva, I'm not sure what you're going for with Lioncourt...

[pedromvilar]

I think she's saying Lioncourt is actually Wood (biokinesis)

[Kappa]

In that case it's not "terrible at basic geomancy", it's "not geokinetic at all whatsoever". :P

[Unbitwise]

You did imply, but it wasn't obvious on first reading, that the combination mages don't have all of the features of their two base elements. (But gods do.)

[Kappa]

I'm writing all this on my gadget so my capacity to glance over my posts in full is limited by screen size.

To clarify: The specific elemental abilities (geokinesis, light manipulation, etc) are specific to their particular elements. I tried to get at that with this part of the OP: "a Water mage who's just a person who happens to be both strongly Earth and strongly Air will only have hydrokinesis and not geokinesis or aerokinesis, but a person with an Earth personality and an Air personality will be an Earth mage as the one personality, an Air mage as the other, and Water when acting jointly."

And yes, gods get it all, every single element.

[Eva]

I was expecting that Wood mages would have some geomantic abilities, but if anyone can be deep enough in denial to think that they're an Earth mage without any ability to affect Earth, it's a Lioncourt. :P

Edit: It probably also helps that being that deep in denial is going to just wreck her actual biomancy.