Fear has A LOT to do with reincarnation and karma. We keep old fears from past lives until we clear the karma (through experience and lesson on earth). I'm sure you've heard of people saying they remember past lives as Atlanteans (i've ordered a book called A Dweller on Two Planets about that). Of course, hard proof of such is hard to come by, it takes a lot of what speaks to your heart and mind and soul. If you have a clear channel to your higher self you can always trust it.