This has also been another curiosity of mine. I have never seen someone so interested in blood type before than my husband was/is. I'm A+, and my husband is B+. I also found that he didn't know much about negative and positive and who was universal donor and all that stuff. He just knew about which blood type was right for what blood type and that kind of thing and what type person A supposedly or what type person B was or O, etc. Just more superstitious stuff that goes over my head...