From working in general rescue for a while, I sometimes get amused by the kinds of 'crosses' people will insist are in a particular dog. People are sometimes very sure that you can see clear breeds and that any cross is an exact mix between the two parents and will look like a half and half. Indeed the latter totally incorrect supposition fuels the designer crossbreed market with people getting cross puppies that don't look anything like the 'cute' one they saw on the internet ad!
Just as a case in point: this puppy is currently looking for a home in Ireland and is KNOWN to be a cavalier/cairn terrier cross:
Doesn't look like it has a drop of cavalier blood. That's the interesting thing about crosses -- they can end up as large as the larger parent or as small as the smaller, they can look entirely like a p/b of one of the breeds and nothing like the other or like a mix OR like *a completely different unrelated breed* simply due to the way the genes mixed; they can throw back to other mixes if the parents are not pure.
Just as a case in point: this puppy is currently looking for a home in Ireland and is KNOWN to be a cavalier/cairn terrier cross:
Doesn't look like it has a drop of cavalier blood. That's the interesting thing about crosses -- they can end up as large as the larger parent or as small as the smaller, they can look entirely like a p/b of one of the breeds and nothing like the other or like a mix OR like *a completely different unrelated breed* simply due to the way the genes mixed; they can throw back to other mixes if the parents are not pure.