Abs are mostly diet, for me.
I was 13/14. Everything I didn't have seemed like magic.
That being said, I see a big difference on me between dieted down abs, dieted down and killing it with ab work abs, and abs I've been killing with ab work before I dieted down. Alas, I try to spend no more than an hour in the gym, so I usually skip out on ab work until I'm dieting.
I posted about this a little while ago, but I've been holding in my gut on most movements. My bodyfat percentage is on the higher side for me right now, but my stomach is flat and hard and I can see ab definition when I flex.