I'm still not convinced about Khan in TWOK. In Space Seed, TOS McCoy would have had to have missed this during the course of his tests on Khan while in sickbay.
I love him to pieces, but I'm sure McCoy missed a number of things that weren't convenient to the plot of a particular episode. Same for Kirk, Spock, et al. Remember "Tomorrow is Yesterday," where Spock conveniently forgot to check whether Captain Christopher would have sired children? Huge glaring
oversight, and something any logical person would check, but nope, and why? It would have resolved the storyline without any drama.