If this article is to be believed, very little. Unfortunately, it probably is at least mostly correct.
Luckily they don't have it here, as far as I can tell, in fact much that isn't listed as organic is still really organic per local articlles, and I cook and bake mostly from scratch. I bake much too large a batch for me and share with my neighbors. A young Texas systems engineer neighbor says he can tell.
Links:
[1] http://shiftfrequency.com/comprehensive-list-of-gmo-products/