First of I don't know what book tells you that an American Pit Bull Terrier is fine with other dogs? If you keep a puppy of any breed from being socialized with all kinds of people and isolated from visitors I could see the dog growing up to being insecure agressive. Pit bulls or any breed for that matter will try to dominate in some ways. My chiwawa tries to dominate ... I don't think a Pit Bull is the right dog for the first time dog owner but I wouldn't consider their dominance in the same level as a guard breed and I have been around AB, CC, Presa and GSD dogs. "He doesn't make friends with you if he doesn't like you?" - with all the respect I think you need to revisit the standard of the true american Pit bull terrier any dog willing to show this kind of human agression has a faulty temperament and should be put down. http://www.apbtconformation.com/temperament.htm All the work the Pit Bull comunity is doing around the world from stopping the breed from getting banned gets tarnished when someone allows a human agressive pit bull to behave that way. Can you post the pedigree of your dogs?