Dogs are pack animals. If you deprive them of contact with other pack members, they'll develop an unbalanced character. Some while ago, trainers would train young dogs using an adult "mentor", a model which puppies would copy with great pleasure. In fact, the best "trainer" for a young dog is not a human being, it is an adult dog. So I think it is a good idea to raise a puppy around an adult, of course, as long as that adult is what you want it to be.