Why do Sphynx cats appear hairless?

Sphynx cats appear hairless because of a genetic mutation that occurred naturally in shorthaired cats and was later reinforced by generations of selective breeding. This mutation affects the development of hair follicles, leading to the absence of a typical fur coat. Contrary to popular belief, however, it is rarely the case that Sphynx cats are entirely hairless—they generally have at least some fine, downy fur.

The mutation was first observed in a cat named Prune, born in Ontario, Canada, in 1966, though subsequent breeding efforts involving that cat were marred by health and fertility issues. The modern Sphynx breed descends from two later, naturally occurring cases of the same mutation. The first came in 1975 when a stray cat named Jezabelle gave birth to two hairless kittens named Epidermis and Dermis in Minnesota. The second occurrence took place in 1978 in Toronto, Canada, where a male and two female hairless kittens were found.

The unique appearance of these cats caught the attention of breeders, who started breeding these cats for this trait of hairlessness. By breeding these hairless cats with other breeds of domestic shorthaired cats and then backcrossing (mating a hybrid offspring with one of its parents or a close relative to reinforce a specific genetic trait), breeders were able to stabilize the hairless trait and develop the Sphynx breed as it is known today.