James Green, You are incorrectly referring to the sweet potato described in the article you cite as a GMO.  The article doesn't say anything about it being genetically engineered.  In fact, it says that it's naturally transgenic.  It's not a product of human scientific activity.  Here' the World Health Organization's statement on GMOs:  "Genetically modified organisms (GMOs) can be defined as organisms (i.e. plants, animals or microorganisms) in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating and/or natural recombination. The technology is often called “modern biotechnology” or “gene technology”, sometimes also “recombinant DNA technology” or “genetic engineering”. It allows selected individual genes to be transferred from one organism into another, also between nonrelated species. Foods produced from or using GM organisms are often referred to as GM foods."  Apparently, you don't even understand the definition of genetic engineering.