Things are a little more complicated than that...for one thing, pretty much all genetics work done today requires customized primers for the process of creating

Things are a little more complicated than that...for one thing, pretty much all genetics work done today requires customized primers for the process of creating lots of identical DNA strands. If you accidentally sent off for chickenpox primers and used them with DNA from your gene donor vegetable/fruit/flower/jellyfish/etc, you would not get chickenpox DNA. Further, I believe that the way DNA strands are identified and recovered is by estimating their size in base pairs and comparing that to the expected result. And samples from the results are sequenced to verify their accuracy, anyways. I believe that there are also similar targeting steps with the CAS-9 proteins, but I don't know very much about this subject. I do think that I know enough to say that accidentally clicking the wrong file will not put chickenpox into a potato anytime soon, though.