Mexico is fighting to phase out genetically modified (GM) U.S.-grown corn. The Mexican government says this will protect its citizens' health and the country's native corn varieties. Yet the announcement provoked strong objections from the U.S., whose largest annual customer for GM corn is often Mexicobetween 2018 and 2020, Mexico bought nearly 30 percent of all U.S. corn exports. The dispute has escalated to formal negotiations under the United States-Mexico-Canada Agreement (USMCA). Mexico ... insists that GM corn threatens human health, and that modified seeds threaten Mexico's agricultural traditions and cultural identity. What began as a wild grass called teosinte nearly 10,000 years ago ... has evolved through millennia of domestication and selective breeding to yield the corn that we know today. Mexico is concerned that GM corn poses the risk of genetic contamination"genes from U.S. corn have a history of crossing the border and entering Mexican varieties. Pollen from GM crops can travel considerable distances and cross-pollinate with the native varieties, potentially altering their genetic makeup and, in some cases, making them less suited to the specific conditions they were bred for. In the U.S., most corn is grown with seed produced by large corporations, which create just a handful of genetically identical corn varieties grown at mass scale.