A while back I saw an essay (article, blog entry, something) about all the different incarnations of the Doctor, and how the personality and quirks of each one could have been influenced by the previous incarnation. Specifically, I recall how the most recent incarnation’s reaction when regenerating (checking that he’s got the right number of arms, legs, etc) is because his last death had been from a high dose of radiation, so he was afraid he might be a mutant. 
But each analysis had a lot of interesting insight into the character(s) and how the new incarnation could be influenced by what the last one had gone through. I can’t remember the details (other than the immediate regeneration reaction for Eleven), and I can’t find the article no matter what I plug into the search engines. Anyone have any idea what I’m talking about or where it can be found?
Sounds like something I read, too, which means it was probably either from here, Cracked, or Den of Geek.
My husband, Doper Andy L, says it’s this:
I may have read a summary or an analysis of that, but that article isn’t ringing any bells for me. Maybe the OP will recognize it though. 
I think I read that too - but I’m not sure it was an article, I think it was on a message board. Don’t remember much of it, but it was definitely about how the various causes of the Doctor’s deaths (or just problems that he may have had durning his Nth incarnation) influenced the next regenerations personality. Specifically, I remember the theory that Five’s kindness and eventual self sacrifice lead to Six’s overwhelming self-centeredness, as a defense mechanism to prevent him from sacrificing himself again.
Found it! TV Tropes Wild Mass Guessing about 1/5th of the way down.
ETA: Looking at it now, I think Dendarii Dame’s article is closer to what you were looking for.
This looks like what I remember reading. Should’ve occurred to me that TVTropes was a likely source.
Glad to be of assistance. Of course, now I’ve TV tropes-ed myself. Shit. I had stuff to do today, damnit!
TV Tropes WMG has one of my favorite Doctor Who theories, btw: That the death of the Seventh Doctor was a hit put out by the Daleks who foresaw the Time War and wanted to dispose of his more manipulative self before getting locked in a strategical battle with him. Of course, there’s a lot of holes there, but still, very fun page.
Hm, none of these is exactly it, because the one I remember specifically mentioned the death by radiation affecting Matt Smith’s entrance, but the first one is the closest to the kind of thing I was thinking of.