The ones I’ve seen haven’t modified the chemical composition of the food, so I’m not worried about eating them. Other uses seem to be to block crop losses by insects and weed crowding.
However, I don’t like companies like Monsanto patenting them, then selling seeds that grow well but have a hidden gene that makes the next generation far less productive so farmers have to keep buying rather than using their own seeds for the next season. A variation of this is if the farmer uses his seeds that still contain last year’s patented genes, the company can sue him. I’d prefer to see far more patent restrictions on the supplying companies.
Another problem is when genes transfer to other plants so the standard weed killers no longer work on them.
In all fairness to Monsanto they did do the research, took the risk, and spent a lot of money to create these crops. In some ways this is not unlike the problem the music industry faces when digital music hit the scene. If you don’t protect your product then everyone can make copies and you lose your entire investment. Monsanto has every right to prevent the farmer from taking seeds from these plants and using them for next years crop.
Keep in mind the farmer always has the option to use plain old un-patented seed stock if he wants to and he won’t have this issue. Its a bit disingenuous to want the latest invention but complain about having to pay the price.
Amazingly enough, back before we had GM crops, seed producers had to spend all kinds of money to develop new crops (which often took years to produce results), taking a lot of risk, and with no way of protecting the final result. When it hit the market, their competitors would simply buy the seeds, and in a year or two, be offering the same crop, yet they still managed to turn a profit.
If you pick up enough seed catalogs, you’ll quickly notice that almost all of them are nearly identical, not only in terms of the seeds they offer, but the photos and ad copy accompanying each photo. This is because most of your seed suppliers have been subjected to the same consolidation that has happened in other industries. This limits your sources of independent suppliers, and even some of the independent suppliers have run into issues where their crops have been contaminated by crops produced by other companies.
GM crops aren’t necessarily evil, but a lot of the ones that have been developed are the product of short term thinking, and failing to understand evolution. In China, they genetically engineer cotton plants to be resistant to weevils, this led to an explosion of other pests that were normally kept in check by weevils, so the crop losses worked out to be about the same, rather than lower.