Game concept
Divergent Culture
The game also links it as Divergent Cultures, Diverge, Diverges.
From the game's encyclopedia
A Divergent Culture is an offshoot of an existing Culture, created by a Ruler.
The Divergent Culture keeps its Heritage, but other aspects of the original Culture can be changed.
The Culture that is diverged from must be at least -9900–200 years old, and the Prestige cost to diverge is based on the creating Ruler's Realm Size.
New Cultures can also appear as a Hybrid Culture.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Divergent Culture is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A Divergent Culture is an offshoot of an existing Culture, created by a Ruler." It is part of Culture. The game also links it as Divergent Cultures, Diverge and Diverges. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.