I wonder if the blood typing thing was because he was
hoping for paternity.
Wikipedia on Conscription in the US:
To increase equity in the [draft] system, President Dwight D. Eisenhower signed an executive order on July 11, 1953, that ended the paternity deferment for married men.
Tammen was missing by then...but I don't know how much "They're going to overturn the paternity deferment!" was in the news in the months before he went missing. If the paternity test was 5 months prior to his April disappearance, that would mean he had the test in November 1952. Maybe he was hoping to at least
not be ruled out as the father of someone's child, so that he could marry and get a paternity deferment, whether or not he was the father. (At least, I remember that being the plot of an old Alan Alda movie.) If it became apparent that that deferment was going to end, maybe he decided to avoid the possibility of conscription by disappearing. Of course, if a woman is willing to marry you and attest that you're the father of her child (whether you are or not), I don't know if you would have had to prove it by blood test to get out of the draft back then; even today, the law is most states is that all children born during a (heterosexual) marriage are legally assumed to be fathered by the husband. Also, he was only a sophomore and had at least 2 years of college deferment left, and the Korean War was already winding down when he disappeared (armistice was just a few months later), but maybe he was looking ahead to the possibility of Vietnam, which was already in the pipeline by then. Having said that, I don't think that's why he got a paternity test, or that he was trying to avoid the draft. I teach adults, and all male students are required to register for Selective Service to get financial aid (and who doesn't need financial aid these days?), and none of them are apprehensive about or even much aware of what Selective Service even entails. (On the other hand, the draft isn't active right now, and plenty of my students eventually go military for the educational benefits.)
I also can't find anything specific about blood type as a possible medical deferment during the Korean War, but current guidelines only list actual blood disorders like anemia:
http://www.apd.army.mil/pdffiles/r40_501.pdf
I would speculate that during the draft, at a time when war was less technological than it is now, and more about ensuring a supply of soldiers for the front line, that fewer conditions would get you an exemption than today, so if it doesn't apply today, it probably didn't then. If anything, I wonder if being O- (universal donor) is what would get you an exemption (rather than having a rare blood type), since you might have been perceived as too valuable as a blood donor to risk. Someone above hypothesized that perhaps the blood test was for a possible Rh factor issue in a pregnancy (if he'd been the father), and I think that's a good theory. My mother is O-, and her pregnancies with my older sister and me (in the 60s) were dicey. My folks already knew that there'd be an issue bloodwise, but that's because my mom was an RN and my dad was military, so they were pretty well-schooled on blood type.
My last thought is that my father did some pretty shadowy things for DoD in Cold War Europe (where we were stationed when I was growing up), and I just don't see Ronald Tammen or the Cox guy being whisked away by CIA recruiters and not allowed to ever contact family again. Janice Pennington's husband, Fritz Stammberger, was a rugged mountain climber and athlete with backcountry survival skills who spoke several languages. Ronald Tammen was a business major who played the bass fiddle. I don't doubt that the CIA did (and does) all kinds of shady things...but I don't really see them signaling generic business majors with dead fish and sending 20 year old kids immediately into deep cover ops. (We often weren't allowed to know where my father was going, what he was doing, or when exactly he would be back. But we
always knew he was going TDY--he never just disappeared.)
And speaking of fish...what I want to know is: Did anyone ever find a fish in the trash, either in Ronald's room or in the dormitory dumpster? I suppose if it was just a dead goldfish, he might have just flushed it...but if it was big enough to necessitate even changing pillowcases, shouldn't there have been a big dead fish somewhere? (I'm thinking that--if there was a fish--it was a sizable one, because even though housekeeping probably automatically supplied a pillowcase with all fresh changes of linen, that doesn't mean a college guy would go to the trouble of changing all the linens unless needed.)
College-age is when schizophrenia, bipolar, etc. often begin to manifest themselves, and 1950s middle America was not a good time or place to be if you were struggling with issues such as sexuality, for example. So I would lean toward something along those lines as a possible reason to either disappear, or at least, to have secrets. (Not that there's any evidence of either in this particular case. But I'm not sure those things were spoken out loud as possibilities at that time.)
Just my random thoughts after reading through the thread--
