Complex sentence: He was a son of Matthew Spandounes and Eudokia Kantakouzene, a daughter of Theodore Kantazouzenos and Helena Kantakouzene, both parents members of the same extended family.
Split into simpler sentences: He was a son of Matthew Spandounes and Eudokia Kantakouzene. His mother was a daughter of Theodore Kantazouzenos and Helena Kantakouzene, both parents members of the same extended family.