GMO foods, within the context of the world-capitalist system, have a couple major pitfalls.
1. GMOs may be copyrighted. This allows large multinationals to, for example, create seeds that expire and/or which may not legally be reproduced and cross-bred, ensuring future profits but at the same time unduely siphoning funds from the third world and poorer farmers in the first.
2. These corporations are under heavy incentives to move their GMO products out into the world without sufficient testing. This has lead to unexpected consequences for those with food allergies and other organisms in the ecosystem of which the crops are a part.