Just like human babies, all kittens are born with blue eyes!
This is for the same reason as in humans − because the brown pigment melanin has not yet been deposited in the irises of the eye, or darkened by exposure to ultraviolet light.
As a kitten develops and matures, their eye color may go through several changes including gray, brown, yellow, orange and green. Typically by the time your kitten is 3 months old, their eyes will have changed from blue to the color they will be throughout their life, there are some exceptions such as Birmin and Siamese naturally have blue eyes.
Once your kitten’s eyes have changed color from the bluish-gray that they were born with, their eyes should not change color after that. If you do notice a sudden change, like if they seem unusually brown or dark yellow, that may signal a serious underlying condition caused by anything from trauma to the eye to feline leukemia. Contact your veterinarian immediately if you notice an alteration in your adult cat’s eye color so that the cause can be determined and treatment can be administered.
When it comes to other kitten facts about the body, it is a very different story. While kittens have similar eyes, their little noses are the equivalent of a human fingerprint, and no two noses are ever quite the same. Kittens also have a stronger and more dominant paw, just like we have a stronger hand. Interestingly, though, in kittens the difference is often gendered, and female kittens are usually right-pawed while their male siblings tend to be left-pawed.