Genetic enhancement allowed scientists to customize a child’s genome before birth. Parents who could afford it could give their children finely tuned immune systems, lifespans reaching into the hundreds of years, and greatly increased general intelligence. Children whose parents could not pay lacked those advantages, creating a stark inequality that passed between generations.
The technology developed gradually through repeated rounds of gene editing in stem cells. Scientists also gathered vast amounts of data on how genes expressed themselves as observable traits, sometimes through unethical methods. This work improved their understanding of epistasis—how genes affect one another’s effects—and epigenetics, which concerns how gene activity is regulated.
As that understanding grew, successive generations of enhanced humans became increasingly immune to disease and resistant to infection. Their general intelligence, measured as the g-factor, improved exponentially, reaching levels equivalent to modern-day IQ scores well over 200.