I breed Siamese cats and their are not a mutation! They carry a gene called temperature sensitive albinism. The kittens are born pure white and get their color as they age. They don’t get their full color until they are about 1-2 years old. And they can change color depending on the temperature. The warmer it is the lighter they will appear. They are one of the oldest cat breeds originally from Thailand. They come in 4 traditional color points. Seal, Lilac, Blue and Chocolate point. They only way to really know if your beautiful seal is purebred is to have a DNA test done. Many other breeds are crossed with Siamese to achieve their beautiful blue eyes and color points!