Genetic engineering

Genetic engineering is a process that involves the direct manipulation of an organism's genes. It is a technology that has been utilized by terrans, the zerg and the xel'naga.

Terran Genetics
The science of gene-splicing was a source of great tension between humanist and corporate factions over the course of the 21st and 22nd centuries intensified as it became more commonplace. With the formation of the United Powers League however, it was decreed that gene-splicing led to the degeneration of humanity. As such, those who had undergone genetic alteration were either executed under the edicts of Project Purification or among those sent to the Koprulu Sector.

In part due to such alteration, a mutagenic strain developed in some of these prisoners' DNA that augmented their psionic potential. However, the "pure" humans of Earth also have psychics.

Xel'naga Genetics
The xel'naga were a species obsessed with fashioning a "perfect" organism, a goal that involved genetic alteration of species. It is through their experiments that many species were seeded upon the worlds of the Milky Way, producing many genetic deviants and mutations. However, only the protoss and later the zerg came close to such perfection, both species evolution having been guided by the xel'naga. While the protoss were considered a failure, the zerg were considered a success, albeit one that backfired spectacularly and turned against their benefactors.

Although the greater whole of the xel'naga were consumed by the zerg, the legacy of their experiments can be said to live on in the hybrid, combining the traits of their most developed creations. Whether this is the work of the xel'naga themselves or another power is unknown.

Zerg Genetics
Courtesy of the xel'naga's genetic manipulation, the zerg developed the ability to direct evolutionary processes themselves. On their homeworld of Zerus, the zerg developed the ability to supercharge and steer evolitonary processes of the creatures they assimilated. This was directed with even greater co-ordination by the Overmind, a role that has now been taken over by the Queen of Blades.