One of the most prevalent technologies of the Known Worlds. Your world may already be familiar with some form of genetic manipulation. Indeed, almost every sentient species has experimented with this technology, even before contact with the Commonwealth. For example, many scholars theorize that genetic engineering helped create the different subspecies of Than. Certainly the different castes' abilities have been genetically enhanced. Perseids use genetic engineering in preference to other technologies, creating semi-organic machines, buildings and devices.
But no species pursues genetic engineering as enthusiastically as Humanity. It is estimated that nearly two-thirds of Humans currently alive have either been genetically engineered themselves or are offspring of genetically engineered parents. Most of these modifications were fairly minor, aimed either at correcting genetic defects or enabling normally frail Humans to adapt to hostile extraterrestrial environments.
One common variation allows Humans to live in intense gravity wells, enabling them to tolerate four or five Earth gees without trouble. Other modifications allow Humans to live and adapt to aquatic environments, poisonous air, or intense cold. And of course, the Nietzscheans have made genetic engineering a way of life, using extensive gene modifications and selective breeding in their ultimate goal of perfecting themselves and their descendants.