Genetically Engineered Foods FAQ Executive Summary • Studies on laboratory animals have shown that GMOs can cause birth defects, high infant mortality rates, fertility problems, sterility, immune system deregulation, and accelerated aging, in addition to many other side effects.enetically Engineered Foods FAQ Executive Summary • Studies on laboratory animals have shown that GMOs can cause birth defects, high infant mortality rates, fertility problems, sterility, immune system deregulation, and accelerated aging, in addition to many other side effects.