Trek’s ban on genetic augmentation was always lurking in the background of the franchise, but it was rarely spoken of aloud. It seemed generally accepted that tinkering with a child’s genes prior to birth … well, it merely wasn’t done in the future. It was not just taboo, it was illegal.
It seems that Khan, the other genetically enhanced tyrants of the Eugenics Wars — and a lot of Earth’s genetic manipulation in general — was perpetrated by several generations of men named Soong.
In “Star Trek: The Next Generation,” Dr. Noonien Soong (Brent Spiner) was the creator of the android Data (Spiner), his evil twin Lore (Spiner), as well as his prototype B-4 (Spiner). Later on, in the above-mentioned three-part arc of “Enterprise,” audiences would learn about an ancestor of Noonien’s named Dr. Arik Soong (Spiner). It was Arik, a villainous character, that had fully implemented an intergenerational gene manipulation project that stemmed from Khan and the Eugenics Wars. Arik was keen to enhance people for his own nefarious eugenics purposes and had been implanting Klingons with altered human DNA to make them stronger. His goals were wholly nefarious, and an illustration as to why altered genetics were banned.
It seems, in so doing, the Klingons began to look more human. This was the in-canon reason why Klingons looked the way they did in the original series, but had enlarged craniums by “Star Trek: The Motion Picture.” It seems the altered Soong genes were merely being thinned by normal Klingon reproduction. At the end of the “Enterprise” arc, Arik realized genetics was not an ethical way to build a superman. Maybe, he posited, an android would be better. It might take a few generations …
And he wasn’t the last we’d hear of the Soong family.