Let’s start with the most controversary topic, GMOs. Proponents argue that all plants and animals are genetically modified. Yes and no. Selectively bred organisms do not contain genes from other organisms, GMO organisms do.
GMOs are banned in Europe. Most GMO tinkering has an economic focus – increasing herbicide tolerance and internal production of pesticide. There has been successful treatment of disease with “golden rice” genetically modified to have beta-carotene. Are those harmful? Who knows. The science is still out.