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Both the Tonkinese and Burmese breeds in the United States trace their pedigrees back to Wong Mau, a small, walnut-colored "poor-quality" Siamese cat brought to California by Dr. Joseph Thompson in 1930. Wong Mau was mated with a Siamese, and half the kittens produced from this breeding were Siamese-colored "pointed" kittens, and half were walnut colored. When one of these walnut-colored kittens was mated back to Wong Mau, three distinct types of kittens were produced: pointed kittens with blue eyes, kittens who looked like Wong Mau with aqua-colored eyes and darker brown kittens with golden eyes. The darker kittens became the foundation of the Burmese breed, and developers of the Tonkinese trace their cats back to those in-between colored, aqua-eyed cats.
In the mid-1960s, Jane Barletta in New Jersey and Margaret Conroy in Canada independently began to produce Siamese/Burmese hybrids, and the color of these brown cats with darker points was called "natural mink." The Canadian cats, originally called "Tonkanese" were recognized by the Canadian Cat Association (CCA) in 1971.
Eventually, crosses to blue and chocolate point Siamese and to champagne Burmese expanded the Tonkinese color spectrum. Until 1984, Tonkinese were allowed to be bred to both Siamese and Burmese to establish a wide gene pool. When the Cat Fanciers' Association (CFA) accepted the breed in 1984, the outcrossings were stopped; from then on, Tonkinese were only allowed to be bred to other Tonkinese.
In warmer climates or homes, Tonks may become lighter in color because the enzyme that creates the color in their skin and hair is heat sensitive.