A question about egg colours

[Lalegid]

Just a question about egg colours, and how colour is determined. I hatched a few wee araucana cross chicks, they had an araucana mother and barred rock father. They hatched from green eggs and, I assumed, would be easter eggers and lay greenish eggs. They've both started laying this week and are laying lovely wee pink eggs! It was a lovely surprise, I'm not bothered by the colours but I would like to know how chicken genetics and egg colours work.
They are such sweet wee girls, I'll take a pic of Muffy later today (she's called Muffy because of her muffy feathers on her face!)

 

[Ridgerunner]

Read this and get back with us if anything is still unclear.

https://www.backyardchickens.com/t/840867/clarifying-brown-egg-genetics

Yeah, right. On a simplistic level, it is really pretty simple assuming you have a basic understanding of genetics. One specific gene pair determines if the base color is white or blue. Brown or green is just brown on top of white or blue. Something like this:

White + no brown = white
White + brown = brown
Blue + no brown = blue
Blue + brown = green

That’s the simple explanation of shades of brown or green. If you did into it your head will spin. But it establishes the principle that the base color is either white or blue. Now to your real question.

At the specific gene pair that determines if the egg shell will be base white or blue, each parent has two genes and will randomly pass one of those to its offspring. The blue gene is dominant so if just one of those two genes is blue the base color will be blue. You cannot tell by looking at the egg if the hen that laid it had one of those dominant genes or two. The rooster had two white genes so his offspring all get one white gene from him.

The hen laid a green egg so she either has one or two blue genes at that location. If the hen had two blue genes she would pass a blue gene to her offspring and those pullets would lay green eggs. That did not happen so she has one blue and one white. It’s just your luck that both those pullets inherited the white gene from their mother.

If you do that cross again, the odds are 50-50 that another pullet could lay a green egg. The odds are the same that she could lay a not-blue egg. It’s going to be 50-50 with each individual pullet but eventually you will get a green egg layer if you hatch enough.

One hatch where the odds were about 30% for green egg laying pullets across the flock, I had one green egg layer out of 14 pullets. The next hatch with the same odds I had 6 out of 7 pullets lay green eggs. You’d think the odds would be closer to that 30% but not with my luck!

What’s kind of surprising to me is that you got pink eggs. The barred rock rooster should have contributed brown egg genetics. With the hens laying green eggs they should have been contributing brown genetics also. Pink is almost an absence of brown genes. I would have expected those eggs to be a lot more brown. Like I said, the genetics of shade of brown will make your head spin.

 

[Lalegid]

Thank you!!! I had a feeling it could be complicated. I will take a photo of one of her eggs and try get an accurate shot of the colour!

I guess the answer is to hatch more and see if I can get a green egg layer!