Monsanto's business practices notwithstanding, what exactly is so terrible about GMO foods?
Selective breeding has been a thing for millennia and that's messing about with DNA, although in an indirect way. Changing foods so as to get rid of traits that are detrimental and add/keep traits that are beneficial is bad, why, exactly? If your opposition is anything resembling "but we don't know that it's good/bad!" then that just means that GMO should be held to a stricter scientific rigour. All things considered, science knows very little about which foods are good/bad for you, including the so called natural foods so the "but we don't know!" can be used for anything you put in your mouth.