I believe that attachment is dependent on multiple variables, including internal issues such as personality and temperment, and external factors such as family life and environment.
I agree. I believe that these internal values can be, and are extremely important in the development of children. Just because a child may start out being secure, does not mean that their inherent personality traits will lead them to continue to be. Similarly, their personality may lead them to become a secure individual later in life even if they did not start out as such.