We've learned that Rodney's original first name was Meredith. Before that was revealed, though, the show seemed to think otherwise, and apparently an intrepid fan analyzed the certificates on Rodney's wall and determined that they read "Rodney Ingram McKay".
I could write that off as show inconsistency, but there's a characterization wrinkle that makes that approach particularly unsatisfying: As far as I can tell, schools issue degrees (and degree certificates) only in one's full legal name. Given that, and given the way Rodney proudly displays his certificates and awards on his wall, it would be strange that no one knew his first name was Meredith until Jeannie revealed that fact.
One option to reconcile all this would be if Rodney changed his name legally before obtaining his degrees, so I've assumed this to be the case. Is that plausible, or is it so complicated as to be unlikely? I know that in Massachusetts (U.S.) in the early 1990s, all one had to do was fill out a form, assure a judge that one was not dodging creditors, pay a fee to the court, and then spend months (and plenty more in fees) updating one's name with various other agencies. A passport obtained years later would not (or not necessarily) indicate the old name.
Is it likely to have been that straightforward for Rodney? Would that fit my fanon explanation? (Sure, his record with the CIA and other agencies probably makes mention of his original name, and I'd guess that Elizabeth therefore knew, but I'd also guess that most other expedition personnel (including the military commander) would not have been considered need-to-know.) I don't expect many around here would have gone through this process, but it's always possible, and the experiences of those who changed their name due to marriage would also be potentially relevant.
If it makes any difference whatsoever, I figure the McKay family to have lived in the Toronto area at least until Jeannie went to university.
My thanks for any feedback!