elemental ethnicity in mortals

Pictured above, left to right: Young adult humans who are have dominant air, earth, fire, and water traits.
Body variants Scarterra has four “races” that transcend most humanoid species. Earthy, fiery, watery, airy each with it’s of set of common traits. Genetics in Scarterra is going to be somewhat Lamarckian. Lamarckism was discredited in the real world, but in a world with magic, Lamarckianism makes sense.
A child can expect going to get 45% of her elemental traits from mother’s traits, 45% of her elemental traits from her father’s traits and 10% of her elemental traits from her parent’s lifestyle. More than 10% if the parents were near a font of magical energy. Fonts of magical energy sort of act as a genetic randomizer, it could creates pockets of local population that have different elemental traits compared to their neighbors.
Because mating is not random, people usually hook up with people like themselves. Because people usually live in the same area and maintain the same professions as their parents, environmental factors usually reinforce their parent's elemental traits rather than deviate from them. All that said, it is certainly possible to be mixed race.
Airy people tend to live near the poles. They frequently live nomadic lifestyles.

Commissioned Scarterra Air couple by Diana Rahfoth

Earthy people tend to live far inland. They are frequently farmers. Thus, earthy people are the most numerous.

Commissioned Scarterra Earth couple by Diana Rahfoth

Fiery people tend to leave near the equator. They frequently build and craft things for a living.

Commissioned Scarterra Fire couple by Diana Rahfoth

Watery people tend to live near the coast. They frequently are sailors or fishermen.

Commissioned Scarterra Water couple by Diana Rahfoth

Fonts of magical energy or unusual land features such as volcanoes or waterfalls can create small localized populations of people that display elemental traits that are not congruent with their general location or lifestyle.

Common Hair Traits

Air: White, grey, silvery (like the moon), golden blond (like the sun), Often curly like fluffy clouds. I haven't come up with any cultural hair styles tendencies though I guess they live in cold places so would be more likely to favor thicker hair for warmth.
Earth: Brown, black, sandy blond, sometimes vaguely metallic. Usually straight and neat. They tend to favor simple utilitarian hair styles. Beards are common and shaving body hair is uncommon.
Fire: Red, yellow, or orange. Frequently frizzy or cowlicky. Children and adolescents often have highlights or accents of shocking colors like purple or blue, but this usually disappears by adulthood. Adults will sometimes dye their hair with exotic highlights to look young. Because they tend to live in warm places, short hair is often the norm.
Water: Various shades of blue, sometimes green or black. Usually wavy and shiny. Water people tend take pride in their beautiful hair and men and women alike usually wear their hair long. Facial and body hair is fairly sparse and most watery people shave.

Common Skin Tones

Air: Caucasian pale. In extreme cases, literally white or semi-translucent.
Earth: Various shades of brown or grey. In extreme cases very dark shades of brown or grey.
Fire: Bronze or in extreme cases orange.
Water: Light blue with a hint of green. In extreme cases, slightly silvery.

Stereotypical Body Type

(ethnic variations between ethnicities in body type are less extreme and less predictable than facial feature, skin tone, and hair).
Air: Long and lanky
Earth: Short and stocky
Fire: Medium build, medium height
Water: Lithe and curvy

Common Eye Colors

Air: Blue is especially common. Silver, gold, grey, and purple are known.
Earth: Brown is especially common. Black, green and various metallic shades are known.
Fire: Grey is especially common. Red, yellow, purple, and black are known.
Water: Green is especially common. Blue, grey, and brown are known.

Stereotypical Noses

Air: Large nostrils
Earth: Large bridges
Fire: Especially round
Water: Small and pointy

The Ravages of Age

Air: Hair loss is faster than the other three. Discoloration is more pronounced than the other three. Elderly air people tend to become gaunt much faster than the other three. They are said to “fade away.”
Earth: Discoloration and body settling is much less pronounced than the other three. Wrinkles are not uncommon any elderly people but they become very pronounced with elderly earthy people. The word “craggy” gets thrown around a lot.
Fire: Unlike everyone else, hair and skin get darker instead of paler. This is nicknamed “cindering.” Baldness is very rare (though that doesn’t stop fire people from shaving their heads to cope with the high temperatures of their typical hopes). "Ashy" is a derogatory term for elderly fiery people.
Water: Wrinkles and skin damage occurs much slower than the other three races. Unfortunately, watery people tend to lose their figures much faster than the other three as their bodies settle into less flattering shapes. They are said to “flow down hill.”

Negative Cultural Stereotypes

Air: Flighty and Unpredictable
Earth: Emotionless and boring
Fire: Hot tempered and hot headed
Water: Manipulative and indirect

Positive Cultural Stereotypes

Air: Creative
Earth: Hard Working
Fire: Brave
Water: Empathetic

I commissioned the talent Diana Rahfoth to make the art for this. You should definitely check out her instagram page of great art.

Beasts Too

Dogs and horses also have noticeably elemental ethnic traits.  Many breeders selectively combine different elemental makeups of their dogs and horses to try to breed for selective traits.
Sheep of Scarterra manifest elemental ethnicity and this has a major impact on their wool in both color and texture.
Cats manifest elemental ethnicity too, but they are difficult to breed under controlled circumstances.
Food animals can also manifest elemental traits but they are less variants because most dairy animals are bred with maximum watery traits for better milking and most food animals are bred with maximum earthy traits to make them meatier and slower. Check the articles on pigs and goats for details.

Diverged ethnicities

• Air Ethnicity
• Earth ethnicity
• Fire ethnicity
• Water ethnicity