I have grown my bangs out to about 18 inches and they were still dead straight. Scrunching my bangs doesn't give them any curl. Even with a curling iron, the curl falls out of the bangs in under an hour unless I use a very strong hold hairspray.
The back of my hair starts to curl as soon as it gets to be about an inch long.
My hair is fine (about 45 microns in diameter on average both in the bangs and the back), very dense, very porous and very elastic.