As a result of thousands of generations of selective breeding and the pressures of competition there are now actually two subbreeds of Siamese - the modern show Siamese, and the traditional or 'appleheaded' Siamese. Modern show Siamese have been bred to be extremely elongated, with bodies slender to the point of emaciation, and a Y-shaped head with an extremely long muzzle and extra-large 'batwing' ears. The traditional Siamese are much sturdier, with a round head and ears more in proportion to their size. Siamese cats often have a kink in their tails, because the original breeders saw that as a unique feature of the breed. In recent years the kinked tail has become a "flaw" and breeders have largely eradicated it from the Show Siamese. Both breeds of Siamese have almond-shaped eyes and like all Oriental cats they are extremely talkative and demanding of attention. They often will engage themselves in crazy antics to get the attention of their people, and often attach themselves to one human in a household. As they are wired for sound, they can meow loud enough to compete with fire and rescue equipment.
All Siamese have a creamy base coat with coloured "points" on their muzzles, ears, paws and lower legs, and tails. The darker Siamese have a darkening of their back and hindquarters as well. Originally Siamese were all chocolate pointed, but now they have been bred in all of the standard cat colours including red, lilac, blue, chocolate, tabby and torty or tortoise-shell. These coloured Siamese are generally known as colourpoints but in all other respects they are the same as the traditional brown, chocolate or black Siamese cats.
The gene that is responsible for the pigmentation is heat-sensitive so all Siamese kittens, although pure cream or white at birth, develop visible points in the first few months of life. By the time the kitten is four weeks old the points should be clearly distinguisable enough to recognise which colour they will be.
Many Siamese are cross-eyed to compensate for the abnormal uncrossed wiring of the optic chiasm, which is produced by the same albino allele that produces coloured points.