Genetically modified crops are plants whose DNA has been deliberately altered using laboratory techniques to give them specific traits they wouldn’t develop on their own. These traits typically make the plant resistant to insects, tolerant of weed-killing herbicides, or both. More than 90 percent of corn, cotton, and soybeans grown in the United States today are genetically modified varieties.
How Genetic Modification Works
In genetic modification, scientists identify a gene responsible for a desirable trait, such as pest resistance, and insert it into the plant’s DNA. The gene can come from another plant species, a bacterium, or even be synthesized in a lab. This is what separates genetic modification from traditional plant breeding: breeders have always crossed plants to combine traits, but they were limited to species closely related enough to reproduce together. Genetic engineering removes that barrier, allowing a gene from a soil bacterium, for instance, to function inside a corn plant.
Two primary methods deliver new genetic material into plant cells. The first uses a naturally occurring soil bacterium called Agrobacterium, which has evolved to insert its own DNA into plants. Scientists essentially hijack this process, swapping in the gene they want delivered. The second method, called biolistic delivery (or a “gene gun”), physically shoots microscopic particles coated with DNA into plant cells. Agrobacterium works well for many crop species and reliably inserts a single clean copy of the gene. The gene gun is more versatile, working on nearly any plant species or tissue type.
A newer approach uses CRISPR gene-editing tools, which can precisely cut and modify a plant’s existing DNA rather than adding foreign genes. When CRISPR components are delivered as proteins rather than DNA, the resulting plant contains no foreign genetic material at all. This distinction matters for both regulation and public perception.
How It Differs From Traditional Breeding
Farmers have been selectively breeding crops for thousands of years, choosing plants with the best traits and crossing them to produce improved offspring. But traditional breeding has real limitations. Corn, even the fastest-flowering variety, takes at least 60 days per generation under perfect conditions, so developing a new trait through breeding alone can take years or decades. Crossing two plants also shuffles tens of thousands of genes at once. Corn has roughly 32,000 genes, so when breeders cross two varieties, they get the gene they want alongside many they don’t, producing unpredictable results.
Genetic engineering sidesteps these problems. Scientists can modify a single gene without disturbing the rest of the plant’s genome. They can introduce a trait that doesn’t exist anywhere in the crop species or its wild relatives. And the timeline from identifying a useful gene to having it functioning inside a plant is dramatically shorter than the multi-generational process of selective breeding.
The Most Common Engineered Traits
The vast majority of genetically modified crops on the market carry one or both of two trait categories: herbicide tolerance and insect resistance.
- Herbicide tolerance (HT): These crops survive application of specific weed-killing chemicals like glyphosate or dicamba. Farmers can spray their fields to eliminate weeds without harming the crop itself. In 2025, 96 percent of U.S. soybean acres and 92 percent of corn acres were planted with herbicide-tolerant varieties.
- Insect resistance (Bt): These crops produce proteins originally found in a soil bacterium called Bacillus thuringiensis. The proteins are toxic to specific insect pests but harmless to humans and most other organisms. Bt corn and Bt cotton have been available since 1996. By 2025, 87 percent of U.S. corn acres carried Bt traits.
- Stacked traits: Most commercial GM crops now carry both herbicide tolerance and insect resistance in the same seed. About 84 percent of corn acres and 87 percent of cotton acres in 2025 were planted with these stacked varieties.
Other traits exist but are far less common, including resistance to viruses and fungi, drought tolerance, and enhanced nutritional content like improved protein, oil, or vitamin levels.
Effects on Pesticide Use
One of the central promises of GM crops was reducing chemical pesticide use, and over 24 years of data from 1996 to 2020, that has broadly held true. Global adoption of GM insect-resistant and herbicide-tolerant crops reduced total pesticide application by about 748.6 million kilograms of active ingredient, a 7.2 percent reduction compared to what would have been used on conventional crops over the same area.
The environmental benefit was actually larger than the raw volume suggests. Measured by an index that accounts for toxicity, persistence in soil, and risk to non-target organisms, the reduction was 17.3 percent. Insect-resistant cotton alone cut insecticide use by nearly 339 million kilograms globally, a reduction of about 34 percent in that crop’s insecticide footprint. Insect-resistant corn reduced insecticide use by 85.4 million kilograms. Herbicide-tolerant canola saw an 18.1 percent drop in total herbicide volume.
The picture isn’t uniformly positive. Some herbicide-tolerant crops, particularly soybeans, showed only minimal reductions in herbicide volume. Weed populations have adapted to glyphosate over time, sometimes requiring additional herbicide applications, which offsets some of the original gains.
Safety and Regulation
In the United States, three federal agencies oversee GM crops. The USDA evaluates whether a new GM plant poses risks to other plants or agriculture. The EPA regulates crops engineered to produce pest-killing proteins, treating those proteins like pesticides. The FDA ensures that food from GM crops meets the same safety standards as any other food. Before a new GM crop enters the market, the FDA conducts a consultation reviewing its nutritional profile, potential allergens, and toxicity data.
Major scientific organizations worldwide, including the U.S. National Academies of Sciences, have reviewed decades of evidence and concluded that GM foods currently on the market are safe to eat. No credible evidence has emerged showing that approved GM foods pose health risks different from their conventional counterparts.
How GM Foods Are Labeled
Since 2022, the United States has required mandatory disclosure of bioengineered ingredients under the National Bioengineered Food Disclosure Standard. The law uses the term “bioengineered” rather than “GMO” or “genetically modified.” If a food is a bioengineered crop sold whole (like sweet corn), the label must say “Bioengineered food.” If it’s a processed product containing one or more bioengineered ingredients, it must say “Contains a bioengineered food ingredient.”
Companies can meet this requirement in several ways: printed text on the package, a standardized symbol, a QR code linking to more information, or a text-message option. The disclosure must be prominent enough that a shopper would notice it under normal conditions. One important detail: if the modified DNA is no longer detectable in the final product (as can happen with highly refined oils or sugars), the food is exempt from disclosure requirements.
What Crops Are Genetically Modified
Only a handful of crop species are commercially available as GM varieties in the United States. The major ones are corn, soybeans, cotton, canola, sugar beets, alfalfa, and papaya. Smaller quantities of GM summer squash, apples (engineered not to brown), and potatoes (engineered to reduce bruising and a potentially harmful compound produced during frying) are also on the market. Many foods people assume are genetically modified, like tomatoes and wheat, are not commercially available in GM form.
Globally, GM crops are grown in about 26 countries. The United States, Brazil, Argentina, Canada, and India are the largest producers. Some countries, particularly in the European Union, have largely restricted or banned GM crop cultivation, though they may import GM animal feed.