We have both a physical mind and a spiritual mind. For reincarnates the spiritual mind enters the fetus once the mind of the fetus forms. Upon birth the physical mind is in close communication with the spiritual mind. As time passes, the normal senses fills the physical mind and the memory within the spiritual mind fades.
Many times a departed soul will flow into a loved one. Thus your uncle could have occupied you body for awhile. They you will see or hear him. Later his soul will flow toward the center of the earth to be collectivized and digitized. He will then be ready for another reincarnation.
Some times a husband will enter a wife and coexist for many years until her death. Sometimes a dead child will enter his or her mother for awhile.