Years ago I had read an article in Smithsonian Magazine about a research project in Russia where they raised foxes, and selectively bred them to bring out the friendliest characteristics. In each round they would take the kits that are most compatible with humans and mate them together to bring out those characteristics.
It was interesting that those foxes soon took on the characteristics we associate with domesticated dogs, such as being fertile only at certain times of the year, instead of all the time, like the dogs' wolf forebears were.
I just found at www.domesticfox.com that you can now adopt these foxes to the U.S. (probably from the same research facility). And they are soo cute!