One of the thirteen children born to Zipporah and Benjamin Mendes Seixas, Hayman Levy Seixas was born in New York in 1792. His was a Sephardi family involved with Congregation Shearith Israel. In 1824 he married Abigail Nunez Cardozo of a Philadelphia, daughter of Sarah Cardozo and Isaac Nunez Cardozo, an accomplished calligrapher and artist. They had nine children.