Genetically engineered foods are among us already, of course. A few are in your grocery store -- though they can be difficult to spot. The Food and Drug Administration does not require additional labeling. And biotech companies don't have to go out of their way to make their products stand out from the real stuff. See what our English relations think of our genetic experimentation. Calgene did place labels on its genetically engineered Flavr Savr tomato. But then there's the company's Laurical canola oil, enhanced with genes from the California bay tree. The oil is soon to be used in the manufacture of chocolate, nondairy creamer, and candy coatings, and already is used to make detergents and soap. Only we don't know which ones. Calgene just says that "the product is available for use."

Proponents say genetic engineering provides affordable, nutritious food year-round but goes easy on the environment because the crops theoretically reduce reliance on pesticides and other chemicals. Critics, mostly consumer and environmental groups, say what goes on in the lab and in field trials cannot predict the long-term effects on human and ecological health. And, according to a Union of Concerned Scientists survey of field-tested food crops, 93 percent of genetic alterations are done to make food production and processing easier and more profitable. Only 7 percent are engineered to improve nutrition or taste.

Nonetheless, with the approval of the FDA and support from the food industry, more of these brave new creations will be heading our way. The question we may find ourselves pondering is not who but what is coming to dinner? Here are a few clues:

Corn Implanted with a gene from Bacillus thuringiensis (Bt) bacteria, Ciba-Geigy's Maximizer and Mycogen's NatureGard corn both have a built-in pesticide -- one that organic farmers have been using topically for years. The first commercial crop was harvested in the fall of 1996 and is now available for use in corn syrup, cereal, and other processed foods, as well as in animal feed.

Manufacturers claim that Bt corn will reduce the use of insecticides ? . But critics say that in just a few years, insects could become resistant to Bt. If that happens, organic farmers would lose one of the most effective natural insecticides available.

Potatoes Monsanto's NewLeaf potatoes also contain Bt, which is toxic to the Colorado potato beetle. As with Bt corn, critics say NewLeaf potatoes may wipe out Bt's usefulness to organic farmers. These fresh spuds and processed potato products hit the shelves last year.

Yellow crookneck squash First planted for commercial use in 1995, the Freedom II squash from Asgrow was spliced with genes from two plant viruses to build resistance to those viruses and increase yields. It was yanked from commercial distribution after less-than-splendid field results. Look for a new virus-resistant squash in about two years.

Squash has been under cultivation in many parts of the United States for thousands of years and has more wild and weedy relatives than other crops, making the risk of genetic transfer more likely. As new transgenic plants emerge in the wild, they may triumph in the competition for water, light, and soil nutrients, resulting in a loss of ecological diversity.

Soybeans Mated with genes from petunias, bacteria, and cauliflower to improve herbicide tolerance, Roundup Ready soybeans from Monsanto have caused a stir in Europe, due to negative consumer reaction.

Because soybeans are an ingredient in many processed foods, scientists have developed tests to determine the soybean's allergenicity, and consumers with soy allergies have learned what types of processed food products to avoid. But since humans generally don't eat petunias, the FDA does not require that the flower gene be tested for allergy problems.

Tomatoes Calgene's Flavr Savr tomato was enhanced with bacteria to toughen it up for shipping and to increase its shelf life. Approved for commercial distribution in 1994 and later marketed under the homey name "MacGregor's," this was the first genetically engineered whole food to hit grocery stores. But Calgene removed it from the market after it flopped commercially.

Milk produced from cows injected with bovine growth hormone (BGH), biotech milk has gotten a lot of bad press. Some dairies, reacting to the public outcry, have labels assuring that their products don't have BGH. Used by Monsanto (remember that name) to increase milk production ("enhanced" cows produce from 10 to 15 percent more milk per day), the hormone may be related to increased health problems in cows. To fight disease, some farmers are increasing their use of antibiotics in dairy herds, which has led to public health concerns over the development of human resistance to the antibiotics.