I also would have accepted the nerdier answer, which is that in the ST universe, humanity went through a whole genetic engineering craze (in the '90s!) that resulted in Khan and a lot of other madness. So we kind of avoided it after that, and just went au naturel with our gene pool.
The franchise actually did make a few attempts to circle back on this topic, usually as a convenient way of explaining why humans in the 24th century aren't all perfectly fit, hyperintelligent, post-Singularity badasses. Genetic engineering had become a taboo. This was highlighted in a DS9 episode, where Julian Bashir was hiding the fact that his parents GE'd his intelligence, coordination, etc. It was illegal, and he was worried he'd be kicked out of Starfleet.
I also would have accepted the nerdier answer, which is that in the ST universe, humanity went through a whole genetic engineering craze (in the '90s!) that resulted in Khan and a lot of other madness. So we kind of avoided it after that, and just went au naturel with our gene pool.
The franchise actually did make a few attempts to circle back on this topic, usually as a convenient way of explaining why humans in the 24th century aren't all perfectly fit, hyperintelligent, post-Singularity badasses. Genetic engineering had become a taboo. This was highlighted in a DS9 episode, where Julian Bashir was hiding the fact that his parents GE'd his intelligence, coordination, etc. It was illegal, and he was worried he'd be kicked out of Starfleet.