I read an article about that in National Geographic years ago. Very interesting stuff. It did take them a long time to domesticate the foxes, and only a very few were friendly at first. I also remember that it said that certain traits were common to many domesticated species, such as spotted coats.
Has anyone really succeeded in reforming a human aggressive rooster? I've yet to see it. I agree that much has to do with genetics, and that is the exact reason why aggressive roosters belong in the stock pot rather than the breeding pen. If you breed from them there's a good chance their sons...