Bavius wrote:The same question can be asked of psykers. I believe there is a spectrum (iirc Eisenhorn covers this) going from completely null to insanely high powered psyker. Null would be one extreme, the Emperor the other. Probably genetic or something.
This is more or less right. The C'Tan created the Pariah gene and placed it in Humanities gene pool. It is a mutation of the likes where someone gets born with it, at completely random times