Well, the "in-universe" idea is that originally they were all clones of one guy, but eventually they started using different "seed stock" and also (once the Empire was in full swing) drafting people as well. Supposely, by the time of ANH, clones were very rare (and generally the higher-ranking guys).Yeah, forgot to mention that. If you go off of the prequels, all of 'em are clones of Jango Fett. Never any confirmation that the Stormtroopers in 4-6 were clones, but one might be able to reasonably assume...I heard a rumor that all the stormtroopers were cloned from one guy!
I know...crazy, right?![]()
Of course, Lucas did tread dangerously close to violating stuff he'd allowed to be established as "canon" as well... but never QUITE crossed that line. So, the Zahn novels, where the presence of new clone stormtroopers was actually noteworthy. Apparently Palpatine outlawed cloning at some point before ANH... probably because he didn't want anyone else doing what he'd done and coming up with an "instant Army - just add water!" to oppose him.