Genetically modified food

Most of us have eaten the Genetically modified food of ( GMF ). This food has been on our table for many numbers of years? This food has the modified organisms that alter their genome through genetic engineering techniques. How does the halal principle in this contexts? These food are grown at different rate from their natural being? How much of the alteration of the genetic modified food is allowed that will not go against the was Allah created? Where is the limit?