Posted by Carmody
(here)

The Fremen prophecy foretells that one day a man will come, 'the voice from the outer world', the 'Kwisatz Haderach'. "He will look where we cannot — into both feminine and masculine pasts."
Frank was indicating that they had been breeding for, what was it, more than a few thousand years, in order to produce an offspring that was 'barely', in the genetic sense, male, but female. Not an uber male but one that had the sensitivity of the female but could peer down, through time, into the male side of lineage. Via being imbibed with the female capacity.
Herbert was apparently indicating that he was trying to insert some form of similar sensitivity into the male side of the duality, but that according to their understanding, the overall genetics indicated that it had to come from the female side of the genetic systems, it had to be born out of the female side.
Paul was not supposed to be born, his mother, lady Jessica, was to have a female child. Thus, for them, according to their breeding program ....Paul Atredies was never to have been born. This was a culmination point of their breeding program and he came one generation too soon, and was outside of their expectations and outside of their carefully laid plans, regarding control and positioning.