The appearance of the offspring of Siamese and British Shorthair is usually determined by the genes of the two breeds. There are many possibilities for their breed characteristics, because there are at least millions of forms of genetic hybrid matching, so the offspring of their crosses The kitten may have the shape of a British shorthair or the hair of a Siamese cat.
Either the body shape of a Siamese cat and the hair of a British Shorthair, or having the characteristics of both cats at the same time. However, mixed-breed cats are generally not popular among people and will not be recognized by relevant agencies. Moreover, cats born from mixed breeds have variable appearances and unstable genes, so they do not have much breeding value.