Arguments for transgenderism almost perfectly coincide with those that can be used for transracialism, transageism and other trans identities. Not exactly identical but there are interesting parallels. Work in progress, coming soon...
First draft. Potential distinction between "race" and "culture", as analogues of "sex" and "gender" for transgender worldview. Race is more, "biological" (for a lack of a better term), and "culture" is more psychological, self-identifying. For transageism: potential distinction between "chronological age" vs "self-identified age" (awful provisory term, I'll have to find something better lol). For age-related identities, one can make a distinction between "precise" vs "non-precise". Non-precise: baby, toddler, child, young adult, middle aged, senior etc. precise: 20 year old etc. "Teenager" can be ambiguous in English since when taken literally, it describes people from 13 through 19 (-teen numbers), but "adolescent" can be used as a synonym and it would be classified as "non-precise". Work in progress for philosophical implications of transracial and transageist identities.