Jaak's father was Andres and his mother was Epp. His paternal grandparents were Toots and Ann; his maternal grandparents were Peedu and Kärt. He had four brothers and a sister, named Jüri, Juhan, Tõnn, Mats and Kärt. He had a half-brother and two half-sisters, named Mihkel, Liis and Margret.