Children are products of their environments because children see what people and learn how to do it. This is how children learn to walk they see others walking and they progress until they can do it, Same with speaking.
Children are not the Products of their environment. All children possess the faculties of learning, which Develop in tandem with a baby's temperament, however, this can only be stretched so far. Babies are not complete blank slates at birth. All babies possess the hereditary information of their parents, and will have genetic predispositions before a social environment can even affect them. In other words, predetermined fundamental aspects of a baby's personality will already exist, before society, education, teaching strategies, parents, and other factors, can affect it.