Over time, we develop predictive mental models (in attempts to minimize psychological entropy) of others and of ourselves based on past experiences with our caregivers. This results in four adult categories of attachment styles: secure, fearful, preoccupied and dismissive. These four styles are not stagnant but a combination of two dimensions 1) anxious and 2) avoidant. Scott Barry Kaufman explained it really well in his last book:

Our brains are prediction machines. They constantly process incoming information and assess how it matches its own expectation models. How our brains process massive information should inform builders of social technologies.