The Dune Encyclopedia
The non-canon Dune Encyclopedia (1984) by Willis E. McNelly quotes the Bene Gesserit Azhar Book, which states that Abomination is "that soul resting quietly within its womb-bed whose entire life is destroyed by a pre-birth knowledge of its ancestors' personae. We cause such a chaotic state if we allow a breeder to take of the Water of Life when she is with child."
In another quote from the Azhar Book, the conditions for Abomination are stated: "First a pregnant Bene Gesserit breeder must ingest the Water of Life ... This chemical, carried in her blood to the womb, activates the fetal psychic awareness and produces a babble of sound and sensory imagery which the un-born is unable to comprehend or assimilate. At birth, this "awakened" baby supposedly sees with adult comprehension because of the active, intelligent, adult memories it now carries at a conscious level. The child, therefore, appears to the uninitiated as extremely precocious but to the knowledgeable as a possible Abomination."
Read more about this topic: Abomination (Dune)