Complex sentence: Jan Sarkander was born into a Silesian (Bohemian-Polish) family, father Gregory Matthias Sarkander and mother Helena née Górecka of Kornicz (Kornitz), at Skoczów in Duchy of Teschen (Silesia).
Split into simpler sentences: Jan Sarkander was born into a Silesian (Bohemian-Polish) family. Jan was born at Skoczów in Duchy of Teschen (Silesia).