Curtiss was born possibly in the village of Constantia in Oswego County, New York. His early life and education are undocumented. His mother’s name is not known, but his father was Hastings Curtiss, who about 1820 moved his family to the nearby village of Central Square, where he built a hotel. In 1824 he served a term in the state legislature, and the next year a newly incorporated Oswego County town was named Hastings in his honor. By 1845 Gaston Curtiss had married Floretta Anna Allen and had at least one son, but four years later he was in debt and forced to sell his real and personal property in order to pay his creditors. In 1850 he was living in Hastings, where he was a merchant and a town supervisor. By 1860 he and his family had moved to the port city of Oswego.