Why be against genetically altered/enhanced fruits and vegetables if you are onboard with human stem cells?

It seems rather disingenuous and a bit insidious to be against genetically altering food to have more vitamins, grow larger, be more resistant to disease or pest, but be so onboard to altering DNA, cells or genetics using unborn humans as a byproduct. To want to use unborn humans because they have yet to breath air or walk to help a living human regain the ability to walk or acquire it because they never had, using genes or plant DNA that didn’t come at a human heartbeat should be a no-brainer. If you can grow a potato 5 times larger than a regular potato, make it more robust to grow in harsher climate on less water and still be more nutritious, how much greater will that and other food benefit mankind? It is easy to take a pompous attitude when you never have to go hungry or never starved to the point of possible death, but if you had I am sure you’d welcome science that can quadruple your food yield off the same number of acres.