In the Japanese language, the fist person can be watashi, watakushi, ore, boku, atai, and so on. Besides, sentence endings used differently by different people. Sometimes, by taking notice of these differences you can guess the writer’s sex and age. I think that this does not apply to the English language; I is I regardless of sex, and so on. Are there any clues to sex and age in written English ?
“the fist person” should read “the first person” because there are no fist people.
“used” should read “are used.”
The clues are more subtle in English. Breadth of vocabulary is a rough indication of the age or at least the education level of the speaker, as is correct use of punctuation. Use of outmoded slang suggests you are dealing with a “wrinkly”. More careful phrasing, and less direct expression of opinions, suggests that the writer may be a woman.
Eg: “wrinkly”: 80’s or 90’s slang
breadth: a word not often used casually by the under 40s
suggests…may be a woman very careful, “feminine” (or academic) expression of opinion.
As the Americans say, go figure