Depends on who you ask. There is a the lack of consensus in the Jewish community, and religious leaders debate the ethics and morality of GMOs.
Over 70 million acres of farm land have genetically modified organisms (GMOs) growing on them.
Study shows that GMO corn causes liver, kidney problems in rats.
Although there are instances of genetic material of non-Kosher animals being used in kosher foods, to date, no one has succeeded in demonstrating that this renders the food non-kosher. The issues are complex, and require a thorough knowledge of Halachic precedent to date.
On the other hand, are we allowed to mess around with species in this manner? This is a whole other issue. The debate centers around the words of the outstanding medieval Jewish scholar, Rabbi Moshe Ben Nachman (known as “the Ramban” or Nachmanides—not to be confused with his predecessor, the Rambam). Concerning the Biblical prohibition of grafting trees or cross-breeding animals, he writes that this is forbidden for a reason of cosmic import: It disturbs the fundamental path of nature. He calls this act, “obnoxious and vain.” Humankind, he says, is given the right to make use of the Creation and to dominate it, but not to disturb its fundamental nature. Speciation is G-d’s business, and off limits to human beings.
when such radical adjustments are being made to the schemes of nature…a responsible attitude is to progress cautiously
The Ramban has a significant retractor on this point: Rabbi Yehudah Lowe (aka “the Maharal of Prague), who lived a few hundred years later. The Maharal, with support from the Talmud, asserts that any change that human beings introduce into the world already existed in potential when the world was created. All that humans do is bring that potential into actuality. The Torah prohibition against cross-breeding is specific to Jewish people and only under the conditions specified by the Torah. Once performed, a Jew is permitted to benefit from the results. I have not come across a significant argument that the current procedures of genetic engineering constitute cross-breeding as prohibited by the Torah.
The truly crucial issues of genetically modified foods are the health and environmental issues. There is a considerable outcry from informed voices that research has been far from thorough in these areas. In fact, there appears to be strong evidence of significant dangers involved. Forty years ago, a horticulturist wrote the Lubavitcher Rebbe about his work stimulating plant growth by means of electric current. The Rebbe expressed his astonishment at the lack of long-term research concerning the effects of foods grown this way on human health, since, “For all these years, human beings have not been eating foods grown this way.” Certainly, when such radical adjustments are being made to the schemes of nature as we are doing now, a responsible attitude is to progress cautiously.
However, greed and the apathy of government agencies have worked against us in these matters. As a Talmudic sage, Rabbi Yaacov of Kfar Chanin, said, “Adam was told to dominate the earth. But the word ‘dominate’ can also be read as ‘descend’. If Adam approached the earth as he was made in the image of the Creator, then he dominates over it. But if not, if he comes as just another selfish creature, then he descends lower than any of the creation.”