Depends on who you ask. The Orthodox Union (the “Union”), a leading kosher authority, has ruled that genetically modified organisms (GMOs) do not violate kosher or kashrut. It asserts that since genes are microscopic, they are therefore botul, or nullified, in the new plant or animal (according to an article on familyfarmdefenders.org). As one kosher certifier in Baltimore put it, “The bottom line is, if it looks like a tomato and smells like a tomato, it is a tomato and may be eaten.” (See this discussion from Coalition on the Environment and Jewish Life (COEJL).)
Such a position borders on a denial of genetics as a science and also does a disservice to those Jews who observe kosher food standards. Genetic engineering, after all, involves the splicing of what is fundamental about any living organism – its true essence in various ACTG combinations. The Union’s stance ignores the fact that genetic modification is performed precisely to take a unique characteristic of one organism and achieve its expression in another. Stated differently, the “microscopic” gene becomes anything but nullified in the host organism–if it was scientists and companies would not aggressively pursue genetic modification. If keeping kosher plays a significant role in someone’s life it would be important to know whether or not their potatoes, for example, have been engineered with pig genes.
But not all Jews agree with the Union’s position on this issue. Jewish groups such as the Teva Learning Centre (an environmental institute in the USA) dispute the Union’s “genes are microscopic and therefore are nullified in the new organism” position and instead believe that genetic modification violates the biblical prohibition against kilayim, the mixed breeding of crops and livestock (see this article from biggreenjewish.org). Similarly, the Coalition on the Environment and Jewish Life has also been highly critical of GMOs (see the article on familyfarmdefenders.org).
On a more local level, Lubavitch Rabbi Yossi Serebryanski of Crown Heights, a kosher supervisor for OK Labs Brooklyn, NY said he has “stopped eating tomatoes and only eats potatoes he knows are organic (see the article on familyfarmdefenders.org). The rabbi said he fears that genes from non-kosher foods, such as pigs or insects, could be implanted in vegetables and Jews may unwittingly break kosher laws by eating them.”
Another interesting twist in this debate is that despite the religious command of “[d]o not crossbreed your livestock with other species. Do not plant your field with different species of seeds. Do not wear a garment that contains a forbidden mixture of fabrics? (Leviticus 19:19)” (see this discussion from COEJL), Jews support GMOs by 55-35% margin, the highest among religious groups polled. In fact, compare this percentage with those of people of other faiths: 57% of Protestants (62% of Evangelicals) oppose biotech based on their religious or ethical views while 37% are in favor; Catholics followed closely behind with 52% opposed and 42%in favor; among Muslims, 46% said they are opposed, with 32% in favor. I would be interested in learning why, among the faith groups polled, more Jews support GMOs.
As a parenthetical, GMOs are also a concern for vegetarians as they may not want to eat foods engineered with animal genes.
Despite the lack of consensus in the Jewish community and while religious leaders debate the ethics and morality of GMOs, logic dictates that foods should be properly labeled so that consumers of all faiths and those of no faith can make reasoned choices.
UPDATE: A new collection of essays gathered in Acceptable Genes: Religious Traditions and Genetically Modified Foods, Edited by Conrad G. Brunk and Harold Coward (SUNY Press, 2009), further explores different religious perspectives on GMOs. See Brittany Shoot’s discussion of the essay collection.