Complex sentence: John Hesselius (1728--1778) was a portraitist that worked mostly in Virginia and Maryland, and son of the Swedish-born portraitist Gustavus Hesselius.
Split into simpler sentences: John Hesselius (1728--1778) was a portraitist who worked mostly in Virginia and Maryland. He was the son of the Swedish-born portraitist Gustavus Hesselius.