* Dogs are domesticated wolves. They share a common ancestor with wolves and have been selectively bred over thousands of years to develop the traits we see in today's dogs.
* Foxes are in a different family than dogs and wolves. While they are all canids, they are not closely related enough to produce hybrids.
It's important to remember that even though dogs and wolves can interbreed, it's not a common occurrence, and the resulting hybrid is often referred to as a "wolfdog." Foxes and dogs are genetically too different to produce offspring.