I have been working on a unique trait for a homebrew race that I have been building for a while now.  

The race has innate access to elemental magic, and each individual can only use one of the four prime elements. (Earth, Wind, Fire, Water).  

I have been mulling over ideas for various unique traits for a while, but have not come up with something that really stands out to me without seeming out of place and ruining the idea of the race I have put so many hours into.

Ideas I have had so far include;
- A tuft of hair on the tips of elf like ears, which is a specific color depending on what element they will be able to use.
- A specific shape to their ears which corresponds to their element.
- Their hair will glow a specific color when under the light of a full moon, corresponding to their element.
- Specific shaped birthmark which is unique to each element. A sort of ember shape for fire, a fading streak for wind, a hard and dark patch for earth, soft water drop for water. 

These are the ideas I've had thus far, but I'm not really feeling them so much.  

So, to bounce ideas around, I bring it to the community.

So you are looking for visible signs that they are linked to these prime elements?

Skin abnormalities is the first thing that pops into my mind, maybe not fully but partial coverage of scales, dirt, tar charcoal spots, feathers. Think it would be cool if this happesn in-game and evolves, it might start out with a aching feeling in their skin, when slowly a small feather begins to grow on their back.

Another one could be certain 'perks', as earth it is known for growth, so maybe their hair grows abnormally fast. Wind brings change so their hair could change form and shape every day.

Another one, but I think is a bit to obious is alterations to their hands and feet, water: gills, fins, flippers, earth: claws, alterations of eyes, wind: weight and wings/feathers etc.

Can I ask how this is different from a Genasi?  They're kind of the default element-based-race, but their appearance is also left deliberately vague so players can basically just make them look like whatever they want.

I deliberately left out a lot of the unique quirks for the race I am working on as I am considering to publish this, as part of a module I have been working on, when I settle on the final draft for it. 

A skin abnormality is part of the idea for a birthmark of sorts.  Happening in game is possible considering that one of the cultural notes for the race is their (ascension) for lack of better term.  It is a ritual (already fleshed out) which acknowledges them and their element when they come of age.  As they intended to be a long lived race (a little longer than dwarves) this ascension normally takes place within the second decade of life. So the idea for it to happen in game is possible, but not as likely.

The hair perks I am limited on because their hair is one of the unique racial qualities which separate them from other races.

Make them even more exotic.  Go with effects rather than skin/hair changes:

Earth:  They are dirty dirty boys.  And Girls.  Think Pig Pen from Peanuts comics.   

Water:  small droplets of water are constantly moving all over their skin.  They do not drip, they flow up as much as down, left, right, etc.

Air:  There is constant wind around their hair.  Basically they always look like the slow motion hair blowing in the wind soft music entrance for the gorgeous girl in the movie/tv show.

Fire:  They are physically hotter.   As in their body temperature is 110 F.   That is hot enough to feel when you are 5 ft from them.

@Mog_Dracov, I like this idea of effects rather than skin/hair changes.

Air and Fire are great ideas as they are, Earth and water I have other ideas on what can be done.  Mostly because I have heard descriptions of Water Genasi with a "Perpetual Sweat" sort of effect.  So, I will steer away from that a little.  

That said, what other ideas does the community offer?