The basic theme of "Frankenstein" is, "There are things Man was not meant to know". The American Spectator : Opposition to GM Organisms Hard to Justify
Opposition to GMO's usually falls into one of three categories: (1) Biotech and "Big Agribusiness" want to make money at the expense of poor farmers; (2) GMO's are unnatural, and hence, undesirable; and (3) GMO's should not be made until proven safe for humans and the environment.
While #1 might be true, it is a matter of business ethics, not science. #2 is the biological equivalent of the NIMBY (Not In My Backyard) argument; it is based entirely on emotion, not facts. Besides, all agriculture is "unnatural." The only truly "natural" way for people to eat is to be hunter-gatherers. Most people probably aren't ready for that lifestyle change.
#3 is the only scientific argument, but it has been mostly addressed. GMO's are already known to be completely safe for human consumption. The vast majority of corn and soybeans in the US are genetically modified. (And corn and soybeans are used in a lot of different foods found in the grocery store.) The concern for the environment is legitimate, but evidence already indicates that GM crops have few adverse effects on the environment. Of course, GM crops need to be carefully monitored for their ecological safety over the long-term, but this is not a sufficient cause to block their use right now.
There might be a case for concern over rogue scientists concocting a The White Plague, but the technology to do this already exists, and scientists out to develop a plague aren't going to register it with the EPA.