Runner Duck color question

[Awaytome]

All of my blue and chocolate female runner ducks have grown white feathers after molts - except one. The chocolates are all four years old, all sourced from the same hatchery, but one of them is still solid chocolate. Anyone have any idea why... what the genetics might be? Or is there something else that influences feather color? Has she found the fountain of youth?

 

[Stipenvlerk]

All of my blue and chocolate female runner ducks have grown white feathers after molts - except one. The chocolates are all four years old, all sourced from the same hatchery, but one of them is still solid chocolate. Anyone have any idea why... what the genetics might be? Or is there something else that influences feather color? Has she found the fountain of youth?

I don't have the answer, would love to see a picture of your flock