Glyphosate, the active ingredient in Roundup has been linked to birth defects in birds and amphibians. It has also been linked to cancer, endocrine disruption, damage to DNA and reproductive and developmental damage in mammals. Crops that are GMO - genetically modified - are round-up ready. This means they have been genetically modified to have Roundup in their DNA makeup. While these crops grow without weeds, the crop itself is genetically ingrained with Roundup.