How did I get a Wheaton chick from two BCM

[Snugglesandwigglespetcare]

Pics of my BCM rooster and one of the hens in the breeding pen. I do have three BCM hens in the pen. One does not have a lot of copper on her hackle feathers like the other two. I have hatched these eggs before and have always hatched black chicks, so I am trying to figure out the genetic glitch. I tried looking up a way to test for underlying Wheaton gene, but cannot find such a test. If someone knows, please pass that on my way.

Oh and before I hear about the SOP of my rooster…I know his golden hackle feathers are not SOP. It is personal preference, tbh. I like the look better than the straight mahogany and black/emerald feathers.

 

[Amer]

The wheaten gene is recessive to birchen. Black copper is red birchen. Ergo, both of its parents must have been carrying a copy of the wheaten gene.

 

[Snugglesandwigglespetcare]

The wheaten gene is recessive to birchen. Black copper is red birchen. Ergo, both of its parents must have been carrying a copy of the wheaten gene.

Really?! Interesting!! Is the only way to figure out which hen then is a carrier is to separate each and incubate those individual eggs?

 

[Amer]

Really?! Interesting!! Is the only way to figure out which hen then is a carrier is to separate each and incubate those individual eggs?

Perhaps.
I would have thought that whichever had more copper would carry wheaten but now I'm thinking maybe that's not the case.