Despite of her looks, Alice has Asian heritage, it is mixed but it dominant. Like in our world, there are Asians of different sizes and shapes, something hard to grasp due to its massive diversity, but with short boi and others I might have covered it a little bit (and no he is not a reference to lookism, I've watched it AFTER building GD6).
Asians are in the upper and bottom tiers of people in the country, the tallest ones come from the most important families, like Miss Tall Legs in black dress and other Overseers, some unknown like Anna and Anri (busty asian), foreigners like short boi and Mr. Ching, mixed like Alice and many others.
The closer women are to the Valley, stronger is their genetics over the males, this is why, in an example of the same family, Vanessa in CT has girls with the hair and eye colors of their dads and Scarlet's daughter hair and eyes exactly like her mothers despite of Stan being the dad. Males genes are taken too, like Jessy that didn't get blue eyes or Patricia that has a brown eyes and Alice and brother that look less Asian, but the power of the Valley is supreme.
This is also why whoever stay shorter usually leaves the valley, and spoiler alert, Vanessa's family comes from there like most women in the country, they were just too short to stay around, different to the Gardens and Gordons who usually had very tall females around.
Additional lore info, Eden and Giselle have begun short because they lived in the mountains most of their lives, Eden for "family problems" and Giselle and Patricia because her mother preferred them to live with "normal people" with their dad to later return to the valley. The influence shows up with Giselle and Eden slowly growing through the story.
Back to Alice, all she has is an outstanding genetics and a whole life living around Domina's Valley, something that empowers her genetics.
BUT other girls can't take advantage of the valley, like Debra or Vanessa who grow on biological triggers, not the Valley's influence.