John Charles Van Dyke was born on April 21, 1856, in New Brunswick, New Jersey, United States. He was a son of John van Dyke (1807-1878) and Mary Dix Strong. He had a brother, Theodore Strong Van Dyke. He was a descendant of Jan Thomasse van Dyke, who emigrated from the Netherlands to New Amsterdam in 1652. His father was a congressman and supreme court justice of New Jersey, and his mother, Mary Dix Strong, was the daughter of Rutgers mathematician Theodore Strong (1790-1869). His cousin was Henry Van Dyke (1852-1933), the minister, diplomat, and professor at Princeton University.