If you want your offspring to lay green eggs for sure you have to have one of the parents with 2 blue egg genes, and one with brown egg genes.Oh I see! But instead of doing easter eggers could I cross him with another blue layer such as a cream legbar? I just want to know what two breeds that they are made up of just in case I want to sell some and want to be able to tell people what mixes they are of.
If you're uncertain if the parent has 2 blue egg genes, or if you know they only have 1, then the offspring could lay brown and not green at all.
The options for chicken eggs are either Blue, which is dominant, or white which is recessive. Brown is a modifier for both of them. Either making a white shell brown, or a blue shell green.
If you're starting with a cream legbar that should be a double blue gene and cover that hen with a dark brown shell rooster, then the offspring should have olive shelled eggs.
What I've run into with every attempt I've made at it is that chickens who should have 2 blue shell genes don't and i get offspring laying shell colors I don't want. Which is why I've given up on it.