I think it was J.J. Abrams said that all of the Stormtroopers were normal people and not clones. Supposedly, they haven't used clones since the era of the prequels, or at least that's the excuse they gave for the stormtroopers in the original trilogy all having a different voice.

Supposedly, a bit of "back-canon" is that Luke was training to get into the academy that trains Imperial pilots.
From
http://www.imsdb.com/scripts/Star-Wars-The-Force-Awakens.html:
INT. STAR DESTROYER - BRIDGE - DAY
General Hux and Kylo Ren walk the length of the bridge.
GENERAL HUX
Supreme Leader Snoke was explicit.
Capture the droid if we can, but
destroy it if we must.
KYLO REN
How capable are your soldiers,
General?
GENERAL HUX
(WITH VITRIOL)
I won't have you question my methods.
KYLO REN
They're obviously skilled at
committing high treason. Perhaps
Leader Snoke should consider using a
clone army.
GENERAL HUX
(YOU SON-OF-A-BITCH)
My men are exceptionally trained --
programmed from birth--
KYLO REN
Then they should have no problem
retrieving the droid. Unharmed.
GENERAL HUX
Careful, Ren. That your "personal
interests" not interfere with orders
from Leader Snoke.
KYLO REN
I want that map. For your sake, I
suggest you get it.
Ren heads off. Hux hates him.