Mothers can be detached or hyper-protective, aloof or encouraging, meddlesome or understanding, and sometimes just plain wrong. Mothers can be a source of both love and harm. The maternal instinct, in other words, manifests itself in a wide variety of ways. Mothers may behave differently from how we expect or prefer, thus causing serious psychological damage to their children and sometimes even becoming so violent as to kill them. Why? And what about fathers? They may be undisputed authorities, or absent, or "motherly". Why has the father's role undergone so many changes over history? Why is it so different from the role of mother? The author follows the development of these two, similarly ambiguous, functions, starting from the evolutionary imperatives - which stem from natural selection - that allow us to understand why parents' love can be so uncertain and variable. The author uses examples drawn from literature, cinema, mythology, and current events to show how our history and culture are influenced by biology.

Grazia Attili is an evolutionary psychologist who teaches Social Psychology at "La Sapienza" University in Rome.