We sometimes tend to project onto others what we most object to in ourselves.

In other words, we often complain loudest about the behavior of someone else (especially someone close to us) when it is behavior we have trouble controlling in ourselves.  We may even accuse others of things they have not done in an unconscious attempt to deny that very kind of behavior or associated attitudes in ourselves.  It is important to look at ourselves before blaming someone else for what we believe has gone wrong in our lives.

We may also project onto others threatening characteristics of our early caregivers over whom we had little if any control.  We do this in an effort to repeat the earlier trauma, this time hoping to gain mastery over the previously overwhelming experience.