I have a 2 year old cat that looks like blue point Siamese cat, but both of her parents were black American Short hairs. Her body structure is the same as her parent's are, but every time I look at her I think of a Siamese cat. Is there a possibility that she could have part of the Siamese breed in her, and she was born with the markings by chance? I'm just curious about this! :3

For the immediate question of how she ended up a blue point: Your cat's parents each only have 1 copy of the colourpoint allele "cs" so they don't show it themselves, they just carry it, and they both happened to give her a copy, making her cs/cs and thus a colourpoint. And speaking of recessives, her parents are also both carrying 1 copy of Dilute and she also got one of those from each of them, which made her a blue point instead of a seal point. BTW, re her parents. do you perhaps mean they are black "domestic shorthairs" from the U.S, meaning non-pedigreed cats of no particular breed / unknown ancestry? American Shorthair is a breed of pedigreed cats. pets question and answers,www.5d2d.com

Now to answer your main question: The answer is yes, almost certainly. But it doesn't say anything about how recent that Siamese heritage is.. It could have been passed down from many generations ago , and it is a recessive trait that can be hidden for generations, as it was hidden in your cat's black-coated parents. So a cat with the colourpoint pattern may be less than 1% Siamese. It also could have got the pattern via an intermediary breed that got the pattern from Siamese.

It's so unusual for a coat pattern to indicate a specific breed in the ancestry, that some people understandably think it must not be true. But people who really know their cat fancy history from old books, periodicals etc.,are aware that the colourpoint pattern DID come to the West via the Siamese. This coat pattern, described by Thai people as far back as the 1300s, was unknown in cats in the West before the late 1800s, when Wichien Maats were first imported and were called by the British "Siamese" or the "Royal Cat of Siam". At that time people commented on the unique pattern never seen before in cats. pets question and answers,www.5d2d.com

Over the course of the 20th century, the genetic code for this coat colour pattern became spread through the random-bred domestic cat populations in Western countries by free roaming unaltered Siamese and their descendants. The Siamese breed became especially popular in the mid 20th century and remember fewer people back then got their pet cats "fixed" and more people allowed cats to roam and mate with other neighbourhood cats.

In some breeds which have the purpose of preserving a natural breed of Western cat ( for example the Maine Coon, or the American Shorthair or the Norwegian Forest Cat),the colourpoint pattern is specifically not allowed in the breed standards, because it is "evidence of hybridization", showing that these breed clubs who wrote the standards also are aware that this was not just a natural variation in Western cats before the Siamese were imported.. (So if you meant that your cat really is a pedigreed AS, she could not be shown in pedigreed classes)

The other breeds of pedigreed cats who have this pattern got it from the Siamese in one way or another. In some breeds, the pattern was intentionally bred into them --. For example the Himalayan (pointed Persian).Persians were crossed with Siamese to get the pattern, then breeders bred back to Persians to get back to the Persian type , but now with the colourpoint pattern.
In other breeds like the Ragdoll: the pointed pattern in the breed came from non-pedigreed domestic cats --- which would have in some way got the pointed pattern from Siamese ancestors.

One pointed breed where some people may argue about its origin is the Birman, since its real beginnings are disputed. Many cat fanciers think that French breeders in the early 20th century crossed Siamese with longhairs, and then, as a sort of marketing gimmick, invented an exotic story claiming this was a breed of "sacred" temple cats in Burma. (next to Siam/ Thailand)..The information is sketchy and contradictory. I don't think there even ARE native longhair cats from tropical Southeast Asia! But in any case, after WW2 the Birman breed was virtually extinct, only one breeding pair left, and at that time the breed was "recreated" using Siamese and longha'\n ired cats. .

One caveat: Of course it's not absolutely 100% impossible that this same mutation at the albino locus that happened in SE Asian cats many centuries ago could have happened much more recently in Western moggies , and if that were the case then there COULD be pointed cats with zero Siamese. It is technically possible. But I just don't think it's likely that by some amazing coincidence, this mutation just happened to occur in Western cats whenever and wherever Siamese cats were imported and kept in any numbers. Much more likely it's the fault of those Meezers.