I have an Imperial Psycher at Psy Rating 3. We finished an epic session last night and I've ended up having to roll a minor mutation at the beginning of the next session. Looking through them I saw that one of them, Wyrdling and one of the Major Mutations, Hellspawn give you a Psy Rating (1 and 2 respectively).
How does this effect Psychers who have already surpassed the Psy Rating 1 or 2 that the mutation gives you?