Complex sentence: Vivian FitzSimons came from a family of naturalists, his father was Frederick William FitzSimons and his mother Patricia Henrietta (nee Russell), both immigrated to South Africa from Ireland.
Split into simpler sentences: Vivian FitzSimons came from a family of naturalists. His father, Frederick William FitzSimons, and his mother Patricia Henrietta (nee Russell), both immigrated to South Africa from Ireland.