Could be something in the family. When "Oddball's" father (my breeding) died. The mother (bought from a local) was left with only her youngest daughter. She (mum) started to change feathering and develop the chestnut feathering. So I swapped her daughter for one of my mums boys and she started to change back. Unfortunately not long after this I lost her. But other offspring of this pair are in my avairys and look and breed perfectly normally.
LML