There was an story in Stephen Baxter's "Vacuum Diagrams" about a eugenics experiment where the participants could only reproduce at like 40 years, then 50, then

There was an story in Stephen Baxter's "Vacuum Diagrams" about a eugenics experiment where the participants could only reproduce at like 40 years, then 50, then 60, etc. The leader was trying to suppress the genes that prevented long life. They probably did some nasty stuff to preserve the experiment, but it's not as bad as just killing all the babies that don't meet the standard of some puritanical leader.