I just returned from watching the movie, and I'm not sure if I heard this wrongly since everything was going on for the first time to me and I was busy absorbing everything in the movie as it happened:
When Finn defected and escaped with Poe, Kylo Ren requested for information on him, whether he is a defective trooper or something. The reply was that, if I remembered correctly, nothing is wrong with him on record, that he had just returned from conditioning, and this is a first-time offence.
Looking back at the movie, who/what are the First Order stormtroopers composed of?
One theory I had in my head is that he is a clone, especially since early in the movie - around or before the time of the scene mentioned in the last spoiler tag, I seemed to have heard the mention of a clone program (or could have misheard it). Some elements that seem reminiscent of it is Finn having been called FN-2187 all his life - like a birth number - and this mention of conditioning. I am reminded of concepts that exist in the EU such as the use of multiple clone templates, and flash memory training that has been used to condition troopers, including Darth Vader's own apprentices partly to instil loyalty. Some may perhaps argue the First Order to be unable to afford clones, but hey they can afford a superlaser the size of a planet instead of a moon...
I may have heard wrong in the movie, however, especially since
When Finn confessed to Rey that he is a stormtrooper, he mentioned how he has never known his own parents. This may suggest he is birth-born, but then again that could have been a clone grappling with his own identity, or some plot device of a clone being deceived into believing what he is actually not.
Regardless of whether my own theory is correct, it seems clear that the stormtroopers of the First Order are different from the stormtroopers of Palpatine's Empire - they aren't simple trained conscripts, but something more. What is this more:
Are they clones, babies seized from birth to be trained and indoctrinated - a practice somewhat similar to what Republic-era Jedi do - or something else?