Earlier quoted context omitted.
Genetic cause is often what is claimed of things that are not very well understood at all. Myopia being one of them for instance. (it's actually often an adaptation process that is actually found to be reversible) Wrt SZ, not only is it very badly understood but a lot of the symptoms can be attributed to biochemical disorders and that does not necessarily imply a genetic predisposition at all. Caffeine can induce psy…
For as long as I can remember I have this thing where I hear sounds, voices and sometimes see things depending on how tired I am. It almost never happens when moving around, it sometimes happen when sitting still and often happens when trying to sleep or wake up in the morning. But always goes away as soon as I move around or start using my brain somehow. However when consuming THC these symptoms are heightened to so…
How do you grade your visualization? Can you create a scene in your head and control it 100%?
How often do you get a random song stuck in your head?
I think that more people are prone to this than they think but they are simply not aware.
Some people start realizing things when they end up trying some kinds of meditation practice and since they are not in control and somewhat clueless about what's happening internally, for some of them it sends them off the rails (hence the stories we hear about meditation triggering psychosis etc...)
Some people never experience such things as well. For some, it comes later.
Talking to oneself is fine. Feeling external thoughts, emotions and even minor loss of self agency in motor control is something else and I think that some rationalizations could make sense. But the current lack of understanding is leading people to handwave (not every scientist is so handwavy of course).
There is an issue of depersonalization such as seems to be the case with your friend. All these things are really not understood and the nervous system alongside the brain is quite inscrutable for now.