Reprinted from Attached: The New Science of Adult Attachment and How It Can Help You Find—and Keep—Love, by Amir Levine, M.D., and Rachel S. F. Heller, M.A., with permission of J. P. Tar­cher, a member of the Penguin Group USA. Copyright © 2010 by Amir Levine and Rachel S. F. Heller.