Hello there! It's a pleasure to meet you.

With having conversations occur in your head, I would argue that "normal" people do this. Then again, I'm only assuming that because I do that. Sometimes this can be a way of coping with certain situations, envisioning how things would go in a particular scenario. However, it can also be ways of preparing yourself for conversations, readying for whatever sort of outcome. I do this and I'm pretty sure my brother does this as well. The only disorders that we've inherited from our parents were Anxiety and severe Paranoia. Though him and I are also very isolated from other people. Do you isolate yourself in any way? That may be something to do with it.

Overall, I'm sure this isn't anything super dangerous or life changing. It's something that many people do, I believe. Especially people who have difficult times expressing themselves, talking to others, isolating themselves, etc. Anxiety(likely Social) may play some part in it, or maybe Paranoia. But I'm leaning more towards the first option.

Thank you for reading. I hope you have a wonderful day!