But in the game Alia is his father's daughter , Am I right?"Late 1980 The 3rd draft of the Rudolph Wurlitzer's script contains an incestuous relationship between Paul and his mother Jessica, and Alia would be both Paul's daughter and sister! Ridley Scott leaves Dune to work on Blade Runner."
Perhaps some way to impregnate jessica prior to Alia's conception so that Alia is actually Paul's daughter?