That is an interesting insight.The study isn’t on children, though. It’s on an adult population. Many of whom would have the ability to form secure attachments, and many of whom would not. Of those who did have the ability, opportunity would be the issue at hand.
I was thinking along the lines that if you didn't get to form secure attachments as a child that you couldn't, you were highly impaired or it would be difficult to do so as an adult.
I am very interested in knowing about how adults learn how to form secure attachments.