Which makes sense, as he sat on the throne from age 9 to 19 - not exactly bulletproof decision-making years. Beyond knowing that, I'd never given it much thought. Turns out, the guy behind Tut was a pretty crafty guy.
"To this day, Egyptologists disagree as to how King Tut died. Some speculate that Ay may have played a part in his death, and fact is that practically as soon as Tut was old enough to actually take the reigns of his own government, he was dead.
Moving quickly, Ay married Tut's half-sister, widow and former step-mother, Ankhesenamen (yeah, they were all the same person) to legitimize his claim on the throne. He ruled Egypt and --cked Tut's mom/sister/wife for four long, fruitful years." - source: Cracked (see #2)