Like many others, I believe there are various other variables that can influence one's higher well-being late in life. Although having a firm and secure attachment with one's parents is an imperative and highly influential variable in the shaping of a person, other influences do exist that play major roles in the development of children. For instance, the environment in which a child grows up in motivates certain traits in an individual, depending on what type of setting it is (i.e. rural or urban). Also, the social class of individuals also plays a key role, for a child with a good upbringing in a higher social class will probobaly have more resources available to it, and thus have more oppurtunities to thrive than a child with a poor upbringing.
Yes, I agree with this. Secure attachment may be able to affect well-being later in life but it does not come down to a simple cause-effect relationship because many other factors may also play an equally or more significant role in that.