A forbidden house is a secure facility in which Chosen women are sequestered. Access to them is controlled by ammonites and subject to the codicils of the Law-that-must-be-obeyed. The rationale for these systems is the priority of knowing with absolute certainty the parentage of a Chosen child
The Chosen believe that it is their blood that sets them apart from other beings. It is in their blood that their semi-divinity resides, derived ultimately from descent—however partial—from a God Emperor. The Chosen believe that, at his Apotheosis, a new God Emperor receives the ‘essence’ of the Twin Gods, transmuting his mortal blood into pure ichor: the divine, burning blood. A child fathered by a God Emperor receives the gift of this ichor intermixed with the blood of its mother.