Khan was already a grown man in 1986 meaning whatever eugenics program created him had already occured.
Trek history and our's seem to diverge after WWII with fashion and countries superficially similar. Certainly the 1960's space race was vastly different with its covert nuclear weapons angle.
We can't judge the entire Earth by a few scenes of 1986 San Francisco. Also if Kirk created our reality where is transparent aluminum?