Babylonian Talmud: Tractate Kilayim Shulchan Aruch: Yoreh De'ah, 295-304 | Mishneh Torah: Hilchot Kilayim | |
Torah: Leviticus 19:19 and Deuteronomy 22:9-11 | ||
Kil'ayim (or Klayim) (Hebrew: כלאים, lit. "Mixture," or "Confusion," or "Diverse kinds") is the Torah-based prohibition of crossbreeding seeds, crossbreeding animals, and mixing wool and linen.
There is a debate whether GMO food is kil'ayim or permissable.
Permissive instances
Although Torah law forbids klayim (shatnez) – "intertying" wool and linen together, with the two exceptions being garments of kohanim and tzitit. Concerning tzitzit, chazal permit using wool and linen strings in tandem only when genuine tchelet is available, whereas kabbalist sources take it a step further by encouraging its practice. However, klayim of animals and seeds are essentially excluded from any permissive instances.
References
Kil'ayim (prohibition) Wikipedia(Text) CC BY-SA