When Alareh, a cabaret dancer, learned she was pregnant, she wished to have an abortion, but changed her mind after telepathic "suggestions" from Darrum. She kept Varen's birth from his father.
Jeffrey was unaware of Varen's existence until after Alareh's death in 2384. He left Starfleet Academy to take custody of Varen and prevent the Enclave from claiming him. They eventually settled on a planet near the Demilitarized Zone. (Star Trek: Pendragon: "Sometimes It Comes In the Clouds", "Promised Land", "Above the Wrecks of Time", "The Hand of God")