GMOs are for many a socially controversial subject. In reality, however, GMOs is just an arbitrary label we use for crops and foods (among other things) that were produced using a specific biotech method. Even if you make the exact same changes using this biotech method and some other method, the former is a GMO and the latter is not regardless of what changes have been done. Anti-science activists have created a culture of fear around biotechnology despite the fact that genetic modification of crops cause smaller, more precise and more well-known changes than crossing two plants on a field does. This is because the latter involve changes in thousands of genes, whereas genetic modification might just involve a single gene.
Scientists have researched GMOs extensively as each new GM crop requires around a decade of toxicological and environmental safety testing before release due to political regulations. The scientific consensus is that the biotech methods behind GMOs are safe and that prominent GM applications are also safe and effective. The real opposition to GMOs come from powerful anti-biotech lobby groups who are exceptionally ignorant of the underlying science.