Pictures of brain scans taken while people are meditating show a gradual loss of activity around the lobes that are thought responsible for one's sense of self ("I"). The meditators report a feeling of oneness with the universe as their trance deepens and the activity in those areas decreases. This made me wonder if we might have stumbled on an alternate theory of reincarnation.
The theory as it stands now says we come back to this life after living a previous life. Some evidence of this is provided by children recalling events in past lives that are too detailed to be explained away as the result of an overactive imagination. What if the memories aren't their's though? What if their minds are in a natural state of oneness until they've had enough experiences to develop a sense of self? The spirits of the departed might be able to take advantage of that state of mind to convey their own memories through children. In a sense, it would be a form of channeling. This assumes a couple of things of course. First, that our souls live on after we die, and second, that the souls remain aware of their own identity while they exist on the continuum of existence experienced as "oneness." As for why they'd bother expressing their memories through children - they might be doing it in an effort to prove to those they loved who are still alive that there is life after death in an effort to comfort them. I know I'd do it if given the chance.
Some science behind the idea
A little more backup from the science cops