Genetically modified vegetables are in the news. Should you eat these "genemods" (GMs in England) or should you avoid them at all costs?

Let's back up a bit. Your wife may not like it when you say that her brother is a louse. You explain to her that's not really an insult. At the most basic level, down where it matters, a louse is not that different from a human being.

How so? Your brother-in-law and the louse are made up of cells. So are you. In the middle of almost every cell is a smaller piece called the cell nucleus. Inside that, even smaller, are long strings of material called chromosomes. It's your chromosomes that decide what you are like, while the louse's decide what it is like.

When you examine a human or a louse chromosome in detail they look remarkably similar. And it's not just the louse and your brother-in-law. It's everything you can think of, from snails to snakes to Susan Sarandon. All our chromosomes are made of the same basic stuff; and that stuff is what makes each of us, physically, what we are.

This suggests a neat idea. Suppose we have a variety of tomato that is very tasty and productive, but suffers from tomato wilt. We also have a wilt-resistant type of potato. The immunity is carried in a particular part of a potato chromosome (let's call it a "gene"). If we could snip just that gene out, and insert it into the tomato chromosome, we might be able to create a new something - call it a "topato" - that produces great tomatoes and doesn't suffer from wilt.

We are not quite that smart yet, although with some foods we are well on the way. Do you believe you have never eaten genetically modified foods? Then take a look at the boxes and containers in your kitchen. See if they contain soy (most of them do). Today nearly half of the U.S. soybean crop is a genetically engineered variety. Crops with genetic modification can have a higher yield, or an extra vitamin, or greater tolerance for weed killers, bacteria, or salty soil. The variations are endless, and the topato I'm describing is a real possibility.

Should we worry about all this? I think we should be careful. We are making things that never existed in Nature. Maybe a "Frankenstein tomato" could have new properties that never occurred to us when we were making it.

On the other hand, plant and animal breeders have been playing this game, through crossbreeding, for thousands of years. There was no such thing as a nectarine or a loganberry before a human developed them, but we eat them quite happily. Even if we hadn't made such things, nature has a way of trying so many different combinations that it might occur naturally in time.

My only concern is that we may be, as usual, in a bit too much of a hurry. We are duplicating in a few years a process that in nature would normally take millions; and we, unlike nature, have to explain our mistakes.

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