It is clear that there is a correlation between the type of attachment you develop as a child and how you and your personality progresses as you grow older, but this cannot be the main reason for the shaping of who you really are considered there are so many other variables that need to be accounted for. Some factors include other adult figures in your life, traumatizing psychological experiences, and wealth and income growing up among other things. So in short, just developmental attachment when you are younger does not account the entire person that you are, but there definitely is a correlation.
I agree. I think a third variable, such as psychological experiences or wealth, affect both attachment in infants, and well-being in future life. So it is not attachment that shapes the future well-being but another independent variable which have similar affects on the dependent variables attachment and well-being in future.