Also, there is evidence that there might be some hidden meta-language on humans as well from studies on how bilingual people/polyglots speak, code-switch, translate, etc.
My native language don't have gender-neutral personal pronouns.
If I want to use pronouns correctly in English, I have to make mental pause before writing he or she to figure it out. Woman/man distinction does not come automatically.
When I use or think in English, my brain has weird rules of its own. Some person can have his/her pronoun constantly wrong. For some it's random. Context and rhythm can also can create pattern.
