A good friend of mine (we've been close now for 2 years) has always been a little strange but just recently he seems more and more comfortable with telling me his rather odd 'personal' thoughts, which is ok but I'm just a little worried over some of the things he says. Like I said hes always been weird. He was never overly social, not shy but just not interested I guess. And when I first met him he often said things that I thought were a liitle off, like he would just state random observations but as if he was talking more to himself than to me. I got past this and  decided to continue our friendship, hes still just as strange but I've learned to live with it. But recently now that we've started hanging out even more (our other friend who usually joins us moved recently so its just the two of us now) he's just gotten weirder and weirder. One evening we were watching TV when he asked me "What it feels like to be me" and I just kind of laughed it off, but he was persistent. Every few moments he'd ask me what it felt like to do this, or what it felt like to have that. I would usually respond by saying "Don't you know that yourself?" and he would just look annoyed. Eventually he wouldn't stop talking to the point where I had to turn the TV off and just look at him for a second. He didn't seem to realize that a lot of his questions were just a little eccentric or confusing. He started again by saying "I'm not like you, so I just want to know how you feel so I can compare it to how I feel." and I gave him another look but reluctantly answered "OK so what do you want to know." I was at this point feeling both uncomfortable and put on the spot. He thought for a long time and then asked "Can I tell you something?" and I thought to myself oh no, what now. he continued by saying "I don't think I'm human." and I had to stiffle a laugh. "What?" I said sarcastically. "I know it sounds stupid, but I don't think I'm a human being." he looked serious and worried thoughts began to cross my mind. "What in the world makes you say that?" I responded to him and he answered with a shrug. he claimed again and again that he just didn't feel human. He said things like he was always different and that'd be'd never been able to find another person simsilar to him. I told him things like he was just unique and that hardly anyone finds someone exactly like themselves, but he went into even more detail. He said that he'd never found himself attracted to other human beings, female or male, and that he'd never truly understood those "unsaid rules of human engagement" and that he always felt as if he was just cruising along among people trying to hide the fact that he didn't understand them. I wasn't entirely sure what he meant by that and told him that people are difficult to understand before you get to know them. But he got more and more confusing by saying that he knows that but what he means is he doesn't understand 'human ways' as a whole and tha he'd never encountered something so confusing as emotions, which he went even further into saying that he doesn't have many emotions and the ones he doens't have are extremely foreign and confusing to him. He even told me that he'd never felt love before and I asked him "what about your family?" He said that he appreciated their care but that he'd never felt that real, deep love towards them or a connection that other families seemed to have. He explained that he'd never felt a 'connection' with anybody. I was a little embarassed to ask 'what about me' but i decided to just blurt it out in a non-threatening way. He told me that yet again he appreciated me but when it came to that connection (he used that word a lot) Its just never there. He explained that this is why he always seems odd to other people because he's just confused about what they want from him, so he just tries to 'goes with the flow' but still ends up looking/sounding unusual. He told me about his beliefs that seem different from what everyone else believes, no matter what its about. And he went on about how he always feels sad because he see's everyone else subconsciously knowing the ways of 'being a person' when he struggles so much with even the simplest human getsure. He told me that he believes that if were to have a baby it would come out looking 'inhuman' or of another species and that he doesn't try to imagine it that way but that this is just the first thing his minds thinks. He also says that his imaginary wife in this equation has a humanoid shape but "no face or nakedness" and again I really have no idea what he meant by that. He told me that he half expects one day to wake up in a different existence where his ways are the norm and he is no longer classified as a human being but some other kind of being. I was rather stunned after his lengthy and personal confession and I just don't know what to say to him the next time I see him. I wonder if i should just forget about it or ask him if he still feels the same way. I'm worried that he has some kind of a problem or something that is leading him to feel/think  this way or if he's just some kind of alien from another planet, just kidding. I'm really  not sure what to do or say about this.