Complex sentence: He married, in or before 1690, Madeleine, daughter of Benjamin Bruzelin, who was a merchant in Rouen, and their first son, also called John, was born on 22 March 1690.
Split into simpler sentences: He married, in or before 1690, Madeleine, daughter of Benjamin Bruzelin, who was a merchant in Rouen. Their first son, also called John, was born on 22 March 1690.