Bene Gesserit
In "Heretics of Dune" (1984), Miles Teg, the former Supreme Bashar of the Bene Gesserit, is noted to be 296 standard years old, and to have a striking resemblance to his ancestor, Leto I Atreides. The son of the Bene Gesserit Lady Janet Roxbrough of Lernaeus (a Fish Speaker descendant) and Loschy Teg, a "CHOAM station factor" chosen for breeding by the Sisterhood for his "gene potential," Miles Teg had been instructed in the Bene Gesserit ways by his mother before being sent to Lampadas to train as a Mentat, a human computer.