Just jotting down a thought I had during my commute this morning...
A large, multi-national corporation essentially has a monopoly on the seeds of a plant that's used as the world's major food source. It just so happens that they've also got a patent on a genetically modified version of this seed, which is the version of the seed that gets distributed to farmers.
The corporation can detect their patented genes in any of the food grown from this particular seed.
Years pass, and suddenly, someone realizes that this genetically modified food genetically alters any organisms that consume it (namely, humans). Additionally, the patented gene embeds itself into the DNA of those that consume the plant. Essentially, the gene now becomes part of the organism. This gene is alos passed on to offspring of the organism.
Now, millions of people have this gene as part of their DNA.
Now the question: When they have children, are they liable for patent infringement?
Let's just say, "yes". So now, this corporation sues most of humanity, wins the lawsuit, but the vast majority of the population cannot afford to pay the damages. Rather than bankrupt the entire population, those who cannot afford to pay become indentured "employees", until their debt can be paid.
(dear scifi screenwriters... you're welcome)