Children of Dune exaggerates for effect the psychological phenomenon of multiple personalities. The Bene Gesserit Sisterhood has long relied on raw melange spice when ordaining Reverend Mothers. Those who survive are filled with innumerable inner lives of their predecessors. When Lady Jessica undergoes the test at Sietch Tabr, she also fills with memories her month-old fetus, traumatizing daughter Alia for life. Older son Paul-Muad'Dib Atreides, converts raw melange on his own whim and survives, proving he is the Kwisatz Haderach - the one who can be many places at once. Paul's genetics coupled with his concubine Chani's spice addiction expose the twins in her womb to particular conditions, giving them more extensive memories than anyone.
The Bene Gesserit have apparently in generations past faced this problem, for they have a strong prejudice against such "pre-born," offering.....
