Some fact checks about plurality
The "Bible of psychiatry" is the DSM. In 1994, the DSM changed the name of Multiple Personality Disorder (MPD) to Dissociative Identity Disorder (DID). This was in response to a moral panic where critics claimed that the condition was fake.
The original and current diagnostic criteria do not require trauma for DID (or MPD) (DSM-III, p. 259; DSM-III-R, p. 272; DSM-5-TR, p. 331).
The international counterpart of the DSM is the ICD-11. Its essential features for DID do not require trauma, either.
Both books say that not all cases of multiple personalities are a disorder or a severe impairment. Psychiatry recognizes that medicalizing them is not always appropriate.
Plurality (or multiplicity) is a community umbrella term for many ways of being more than one person in a body. Psychiatrists who know enough about DID are aware of it. Plurality includes but is not the same as DID.
The community has always included plurals who formed for reasons other than trauma. Dividing the community by excluding non-traumagenic plurals and calling them fake is new. That only started in August 2014 on Tumblr, unheard of elsewhere.
When that started, a trauma-caused DID system created the word "endogenic." This means plurals who formed naturally rather than from trauma. The Lunastus Collective coined it in solidarity with them.
(Similarly, the coiner of another umbrella term, "alterhuman," is a member of a traumagenic OSDD system who supports endogenic plurals. The purpose of that word is for plural systems to unite with other sorts who differ from usual definitions of human individual, valuing what we do and do not have in common, instead of in-fighting about who is more legitimate.)
Community historian LB Lee gives several good reasons why-- as trauma-surviving plurals-- they choose not to call themselves "traumagenic" or divide the community by origins. If I may briefly paraphrase a couple of these: If you see suffering as your whole foundation of who you are, then you have a more difficult time envisioning a better situation. If you want others to respect you, a losing strategy is to put down people who are seen as similar to you.
Neither psychiatry nor the greater community of plurals see trauma history as an important distinction in determining whether someone is plural.
