Fiction is rife with characters who always speak in third person. Often, such characters are portrayed as having a native language or culture that lacks the concept of a first person, and hence they are supposedly unable to grasp the first person when speaking English (or whatever fictional language is being rendered as English). Often such characters don't seem to have problems understanding other English speakers who do freely use the first or second person.
Are there any examples of this in real life? Are there any cultures, whose members are known to have difficulty mastering the grammatical first person when they learn English, even once they learn English at an advanced level? Are there any known pathologies that produce such an effect?
I know there are examples of people who at one time spoke about themselves in the third person, for various reasons. However, to my knowledge these are always either out of choice (ie. the person can speak in the first person, but chooses not to for some reason, such as dramatic effect or politeness) or a trivial lack of competence (ie. the person otherwise understands the first person, and can use when speaking other languages, but happens to have a very rudimentary knowledge of English and avoids first person due to not being familiar with the grammar).