“John Bowlby believed that attachment styles are a function of life experience—especially of our interaction with our parents during infancy. A person will develop a secure attachment style if her parents are sensitive and responsive to her needs. Such a child will learn that she can rely on her parents, confident that they’ll be available to her whenever she needs them. But Bowlby maintained that it didn’t end there; he believed a secure child would carry this confidence into adulthood and future relationships with romantic partners.”