In standard Modos, PCs choose a race by writing it into their character concepts. Advanced Modos, (the one that has yet to see the light of day) will instead grant one bonus perk to determine race at character creation, as follows:
Human: fearless or tough
Elf: sleepless or mana
Dwarf: owl’s eye or stubborn
In addition, any race can choose to take Large Size or Small Size instead of the above perks, to become a giant or dwarf of that race.
Medieval Modos is a place of significant genetic variation, but most people exhibit none of these features. Those that do are considered blessed by the gods or, depending on the situation, cursed.