We speak the language of the group we want to belong to. Whatever it is the particular choice of words or the whole language, we speak in a way that the group of people we want to be part of speak.
By language here I do not mean just the languages, but rather all the choice of words and way of speaking. Language is the shared culture which then becomes shared identity. Sharing the familiar language indicates trust and trust is the basis of societies.
We pick up the cool words from people who we admire. In the same way we’ll learn the whole language much easier if its’ in our desire to associate with that language group.
Because humans are super sensitive herd animals, we pick up the language from the alphas of the groups. And it just isn’t limited to spoken language is the body language and manners as well.
Although the unconscious parts are obviously unconscious, when we become conscious of this, we can take a bit more conscious and responsible choice on what kind of language and manners our unique self wants to express.