My pom is a singleton. He is 2 years old now and has no behavioral issues. I actually took him at 6 weeks, I work at a vets office and I take him to work with me everyday. He has been overly socialized with people and other animals. All of us bring our dogs so he grew up with a Norwegian Elkhound, Am Staff, Boston, chorki, havanese and a dachshund. But I went overboard with the socializing 1 because he was a singleton and 2 because he is a pomeranian. I also started training him about a week after brought him home. However, many of the singleton puppies we see at work are all brats who have no boundaries and will bite you if you push them.