After chapter 1, I suspected that Familie was doing a deranged eugenicist project, given that their program divided the girls in each generation into distinct groups ("classes") and the girls in one group ("insemination") were always tasked with delivering a new baby every three years. That sounds like selective breeding, so Kurumi and her cohort having a significantly altered genome is sort of plausible given enough generations. "Non-human primate" is a bigger stretch because e.g. the Neanderthals were quite different from Homo Sapiens but whether they were a different species or just a subspecies of H. Sapiens is still debated.