why are some eggs white and some brown

Some eggs are white and some are brown primarily because of the breed of the hen that lays them. The eggshell color is determined by genetics. For example, hens like White Leghorns have white feathers and white earlobes and tend to lay white eggs, whereas breeds like Plymouth Rocks and Rhode Island Reds have darker feathers and earlobes and lay brown eggs. All eggs start out white because the shell is made mainly of calcium carbonate, which is naturally white. Brown eggs get their color from a pigment called protoporphyrin, which is deposited on the shell as the egg forms in the hen’s oviduct. This pigment comes from the breakdown of hemoglobin and is only applied near the end of shell formation, so it colors only the eggshell's exterior. The difference in shell color does not affect the egg's interior nor its nutritional content, which remains essentially the same regardless of shell color. In summary, the shell color difference is a result of the hen's breed and genetics expressing particular pigments during egg formation. There is no inherent nutritional or taste difference between brown and white eggs.