To help support your position, corn has been modified to produce vitamin C. Vitamin A typically comes from genetically modified soy. Riboflavin mostly comes from genetically modified microorganisms.
These additions are a concern to the gmo free vitamin consumers. Both https://www.geneticliteracyproject.org/2016/05/03/vitamins-n... and http://www.non-gmoreport.com/articles/oct08/vitamins_gmo_cha... make this claim - both sides. I'll accept it as true.