The modifications inherent within GMOs are highly specific and specialized within their targeted function, specifically limited to areas of plant growth cycles, and resistance to specific organisms, ie, molds or pests.  The ingestion of these foods are broken down within human digestion, such that their constituent molecular bases are synthesized the same as any food. Food not absorbed is simply excreted.  The possibility of say... oncogene synthesis, or horizontal gene transfer and the genesis of prions from plants modified isn't plausible as there is no chain mechanism to enable this.