Let’s say you’re growing your own sweet corn that’s from a heritage seed exchange, or even better, from your own family’s seed. But a neighbor, even miles away, grows GM field corn. Corn pollinates via the wind. Your sweet corn picks up the Roundup-ready gene. It happens.
Same for soybeans and, before long, everything else.
And if you want something to worry about, there are now Roundup-resistant weeds that persist where they’re not supposed to be.
Some guidelines, though:
1. Organic food is less likely to be contaminated, but currently there are no labeling standards to help you know.
2. Locally grown small-farmer food has a better chance in this regard too. Look, a smallish number of huge farms produce huge fields of non-GM items too close to their own huge field of GM food.