It's difficult to make up later for inadequate socialization in a dog's youth. (dogcare.dailypuppy.com)
They relate fairly with strangers, though may become rather reserves with inadequate socialization. (dogingtonpost.com)
The majority of dog bites result from inadequate socialization of puppies and lack of basic obedience training.Most people are bitten not by strange dogs, but by dogs they own or that are known to them. (animaladvocates.com)