Put simply, Chimerics are genetically-engineered or modified organisms.
The situation is far more complicated, however, by the fact that chimerics
can evolve and develop in unpredictable ways, becoming noxious parasites
or multiplying herders. Parasites are described in another section. Chimerics
are their benign cousins. Chimerics range from seemingly-normal cows with
enlarged udders to exotics such as miniature rhinos and the all-new runt
which resembles a heavy-set pony/camel cross that can go for two weeks
without food or water and is amazingly strong.
The completion of the Human Genome Project in 2003 freed up huge resources
in the genetics industry. Increases in computing power made gene-identification
much faster than previously possible while the improvement of gene-splicing
and other modification techniques allowed a debate on the nature of
genegineering to emerge in the Noughts. That debate was won by pro-choice
geneticists with backing from industry amidst the general tolerance of the
public. Huge advances were made in the 2010s - including the discovery of the
now-common Clotis generator - which culminated in the alleged deployment of
grown creatures bred for war into the jungles of Sumatra by the US Special
Operations Command.
The War changed all that. Everyone remembers that war as the Dirty War, for
good reason. All the human mastery of genegineering was turned towards
death and corruption. A billion people died, and everyone was afraid for
their lives in a world suddenly thrown into ecological disaster and
biological backstabbing. Mutant organisms roamed like wildfires from one
hot zone to the next, with scientists' supposed anti-species cures only making
things worse and accelerating the fatal cycle of hyperspeed evolution.
The consequences of this disaster were predictable; a complete clampdown
on genegineering and other technologies in the form of the draconian
Technology Control Regime (more on this here).