The research into the cross epigenetic effects of GMO crops on neighboring heirloom species is still in its infancy, and may even be deliberately underfunded in order to prevent further opposition to GMO. There are a lot of unanswered questions.
Either way, I demand a right to know if I'm eating GMO or not, not just because the modified foods themselves may be having unknown actions in the human body, but because GMO drops can withstand high degree of chemical saturation without dying, which means higher chemical burden for anyone eating that. IBS, IBD, leaky gut and other bowel diseases have skyrocketed in the U.S. in the past 10 years. Diseases like ulcerative colitis have risen by something like 400% in the past 12 years. Clearly the food system needs some reform.
We already know from ground reports that 48 hours before some crops go to market, they are saturated with pesticides and herbicides to such a degree that workers are advised not to enter the fields without hazmat suits.
People have a right to know what they're eating. Also, the political lobbying by Monsanto and other huge food corps is really gross. They are trying to take over the food system, blatantly, so that there are no alternatives but their crap.