People aren't really that much different from one another, you can probably assign a general group to each person and it would all be logical. What makes people different is how they react to certain situations, aka their personality. Without personality we would all be rather bland automatons running amok.
It could be argued that the brain is you, but with ideas like transferring consciousness I beg to differ. The brain it seems is just the processing and storage rolled into one while housing consciousness; but how is it housing that?
In my beliefs every physical object is tied to a spiritual one, whether the spiritual part actually contains anything useful depends upon the object. With that the spiritual side of the brain must be where we really are and our bodies are just along for the ride. I would like to think that on the spiritual side is where feelings, consciousness, and other intangible things reside.
Not all connections between the physical and the spiritual are created equal which would cause bad connections between the two objects. If say the connection between the brain and the spiritual part of it has a faulty connection for feelings, it would cause all sorts of issues. It may be easy to conclude in that regard that this is the cause for mental issues if not caused by malformed data or damage to the brain.
tl;dr: In my opinion, the brain has a physical side for processing and storage of raw data and a spiritual side for feelings and consciousness. These sides don't always mesh well or possibly one side has some sort of damage it may just be some sort of connection problem between the two.