Are Genetically Modified Organisms (GMOs) Kosher?


Q. Are genetically modified organisms (GMOs) kosher? I have heard that they can splice the genes from one type of plant into another. For example, canola seeds can be modified with the genes from the California Bay tree. Does this affect the kosher status of these foods?

A. The Torah (Vayikra 19:19) forbids mixing different species of plants (kilayim). The Mishnayos in Tractate Kilayim list specific activities which are included in the prohibition. Included in this list, is the prohibition of grafting a branch from one species of plant onto another. On a conceptual level, mixing genes from different species can be viewed as a similar violation.

However, Rav Belsky, zt”l ruled that GMO’s are kosher. He explained that the prohibition of kilayim only refers to the specific actions that the Torah or Chazal forbade. Other forms of mixing species such as splicing genes are permitted. As another example, one is permitted to plant a fruit tree of one species next to a tree from another species, even though the trees will cross-pollinate.

Although Ramban (Bereishis 1:11) explains the reason for the issur of kelayim is that by mixing species one is contradicting the command that Hashem gave for every species to be created “l’mineiyhu” (to its own kind), and one might conclude that it is forbidden to mix and create new species, nonetheless the actual prohibition is only violated if it is done in one of the ways specifically proscribed by Chazal. Furthermore, with the exception of klei ha’kerem (planting vegetables in a vineyard), even if plants are grown through a forbidden act of kilayim, the resulting fruit remain kosher.

Click HERE to hear Rav Belsky, zt”l discuss the issue of GMOs. The topic begins at minute 30 until minute 38.

This column comes from OU Kosher’s Halacha Yomis dedicated in memory of Rav Chaim Yisroel ben Reb Dov HaLevy Belsky, zt’l, Senior OU Kosher Halachic Consultant (1987-2016). Subscribers can also ask their own questions on Kashrus issues and send them to These questions and their answers may be selected to become one of the Q and A’s on OU Kosher Halacha Yomis.



  1. Agree with number one. Torah has never taken into account that which cannot be seen. esrog is nireh l’anyim. Bugs in water is nireh L’anyim. Why should this be any different?


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