Even though attachment can play an important role in shaping someone's well-being in the future, other factors can still have huge impact. I think the environment that person lives in, and the experiences that person have definitely play huge roles. For example, if a person lives in good environment, is surrounded by good people, and does not have any bad experience, then this person would be better off in the future. However, if the person is totally opposite from what I just mentioned, then the person would develop in worse way.
