The James Leininger case is one of the most compelling reincarnation cases in existence.
Reincarnation is the return of a soul, or spirit, to corporeal life, but in another body newly formed for it and having nothing in common with the old one. A vague memory remains of the perceptions acquired in previous lives, giving the incarnate spirit what you call innate ideas.
Read these books:
"Soul Survivor: The Reincarnation of a World War II Fighter Pilot"
"The Spirits' Book"
Carol Bowman's "Return From Heaven: Beloved Relatives Reincarnated Within Your Family"