Understanding transgenderism.

[John 6IX Breezy]

This did not originate with me, "But, is transgenderism hardware or software?  Or, perhaps, more appropriately, firmware?"  I would opt for the third option.

Every psychological trait is heritable, and as such, every trait is multivariate. Things are the result of interactions between many moving parts, therefore, thinking in terms of single causes usually leads to problems and inconsistencies. That said, to respond to your question, I would place it at the level of software. That is the level at which it seems to manifest itself, and the level at which identities of every sort are constructed by individuals.

(I don't know enough about firmware to use it as a metaphor.)