The truth is there is very little known about egg color. So why is my eggs that color? While chicken genetics are complex, I will try to keep this simple.
Blue eggs are blue because of the chemical oocyanin contained in the shell. The blue egg shell gene is dominant and considered a “true” egg color.
White is a recessive gene color and a mutation. Technically white is no color at all as it is the absence of a modifying blue or brown gene. The white eggs you get are from hens that most likely have the pr gene in them which inhibits any brown gene making your eggs very white.
Now on to brown. There are 13 genes proposed by scientists that create brown eggs in various shades. Brown eggs are not actually brown shells, but rather a coating of ooporphyrin deposited on the exterior of the shell that is a hemoglobin response in the chicken. You can actually scrub the coating off the egg with a kitchen scrubby. Try this with your kids for fun.
Finally is the green or “olive egg”. This is a combination of two genes present, a blue and brown. Essentially green eggs are blue eggs coated with brown ooporphyrin. The heavier the coating of brown the deeper the shade of olive. We breed olive-eggers on the farm to make our cartons of eggs extra special.
And that is the skinny on why your eggs are the color they are.