Hi poppy,   I cannot diagnose what is going on with your friend because I am not a professional who treats schizophrenia.  However it seems to me that he could possibly not be demonstrative physically or spontaneous with his feelings.  The whole debate of "nature versus nature" has been discussed elsewhere in detail.  I will tell you that he needed to be nurtured as a child so that his nature could be validated and expressed.  Figuring out the root cause of his unemotional tendency is not the solution.  If he is not experiencing psychosis or delusions or paranoia, there is a chance his upbringing and environment with the abusive father could have contributed to his lack of emotion.    It is easier said than done when abuse was involved, however, at some point in an adult child's life he will have transcend the hurt and pain and forgive and move on.  I'm not sure his endless comments about his mother or father serve him well.  He may want to consider therapy with a therapist trained to serve clients with a history of abuse.   Also it is possible for your friend to have a very, very mild form of schizophrenia howewver like I say I'm not the person to tell you that.  At this point I would say you could suggest he talk to a therapist if you feel so inclined to do this.  He may be afraid of getting close to people, or be afraid of showing emotion, because of the fear of what the other person will do to him.  Right now it seems he is vulnerable.   Regards, Christina