Here's why:
* Melanin Development: The pigment melanin, which determines eye color, takes time to develop fully in kittens.
* Temporary Blue: Kittens are born with a lack of melanin in their irises, leading to their initial blue eye color.
* Permanent Color: As they grow, melanin starts to accumulate, and their eye color changes to its permanent shade, which can be green, brown, amber, or even copper.
Keep in mind that some kittens may retain their blue eyes permanently, particularly those with certain breeds like the Siamese, Balinese, and Himalayan.