My single-breed dog doesn't look like just one breed. How is that possible?

Even in single-breed dogs, it is ultimately several genetic trait results (and not necessarily their breed), that are responsible for appearance. 

While breeders tend to strive for consistency in these traits to match a breed standard, it is still possible for them to pass on genes that could potentially give a single-breed dog a unique look. 

Detection Thresholds

Additionally, dogs with a single-breed result can sometimes have a very small percentage of DNA (about 1-5%) that represents a separate breed. 

These very small portions are typically undetectable by DNA test, but can still impact a dog's look.