Another variable that could affect a person later in life depends on the socioeconomic upbringing, as in whether the child is raised in a wealthy or more impoverished area, or whether the family lives in a very remote vs. populated region. Also, the amount of hours per week that a parent works (and thus can't spend time with the child) will affect how comfortable the child is with the parent(s).
I think this is a valid theory because it addresses both the attachment style and well-being later on in life. Socioeconomic status could influence how often a parent is around, such as if they are usually busy working or if there is a babysitter. Also, the population density could be a factor with how many other interactions the child is encountered with and influence their upbringing. All of these things can affect both attachment style as a young child and how they think of well-being in life.
