It is no secret that I have a fondness for anthropomorphic animals. From a storytelling standpoint, they allow the audience to instantly have access to facets of a character's personality that would take quite some time to explore through other means. It also allows the storyteller to play with those stereotypes and more easily surprise the audience with a character that acts against its apparent nature.
That, and they happen to look cool.
Despite the very silly resentment that exists against them in contemporary internet culture, I decided that it was worth including anthropomorphic animals in my setting, as the anthromorph race.
Technically a human subrace, anthromorphs are genetically human, though for the purposes of roleplaying they're treated as a separate race due to their special abilities. Their collective animal features come from a group of common ancestors who were cursed by the goddess Venrisha to appear half-animal. This curse takes the form of a genetic marker, so that the child of two anthromorphs is very likely to be an anthromorph (though can be human in rare circumstances), and the child of an anthromorph and a human has a reasonable chance to be one or the other. The gene itself is a dominant one, so a child of two humans can never be an anthromorph.
Which animal type of anthromorph a child will grow up to be is based largely on personality. The marker itself selects animal type based on the other genes and traits that the child has, and from that information, sets the infant on the path of development into that particular type of animal-man. When families of anthromorphs share a homogeneous animal type, that type will generally not fluctuate much from parent to offspring. When two anthromorphs of different types mate, the animal type of their offspring is completely up in the air.
The major reason why I decided to handle anthromorph genetics in this way is that I did not want their total population to be very large. Anthromorphs represent one percent of the human population at most, and so the sizable breeding population of a single type of anthromorph would be impossibly small if I kept the available types wide and varied. In order to have a wide variety of anthromorphs with a small, spread-out population, I decided to make them all a single breeding population, with an anthromorph's type being a variable that did not entirely depend on parentage.
Also, I made them genetically human because I find crossbreeding in most fantasy settings to be inherently silly. I don't plan on there being any "half-breeds" between godtouched races. Considering that my anthromorphs already bend this rule, and have a "human shape," I decided to simply make them a part of the human race and call it a day.
The ability for a human character to successfully have a child with an anthromorph is a small bonus, from a storytelling perspective.
As for the type of animal an anthromorph can be, any mammal is fair game. Birds and lizards are not uncommon, and in rare circumstances, there have been anthromorphs who are fish, insects or arthropods. In order to deal with the sheer number of possible animal types, an anthromorph character will simply choose from a list of generic animal abilities at character creation, such as night vision, a powerful bite, a powerful sense of smell, limited sight, increased movement speed and carrying capacity (by moving on all fours), thick fur that provides warmth, natural armor plating, or even a prehensile tail. In this way, an anthromorph player can almost create their own custom subrace.
Similar to anthromorphs is the disease of lycanthropy. Also created by Venrisha, the Aarnian variety of lycanthropeism has not yet been ironed out, and there will be a post when I have decided between my various were-options.