Actually I believe in a kind of soul, a electric/magnetic field caused by brain functions. When someone dies the field stays temporarily near the body or the place where the body died until it fades away. The time it takes a "soul" to fade depends on the original person's will or something similar. The soul can perform very simple actions (move something very small or generate a minor visual effect) but as this takes energy and the only energy available to the soul is it's own performing actions is at the expendure of it's lifetime.
If a pregnant woman passes trough one such fields there is a small chance the elder soul suppresses the foetus' causing what we define as reïncarnation.
This theory explains some supernational phenomenons but by far not all. I'm not totally satisfied by it, any comment?
As you've probably guessed I'm atheïst/agnost
. I don't believe in anything supernational right now, but I'm open to any belief or superstition if it makes sense to me.