Lionel Moses was the son of Joshua and Sarah Brandon Moses and brother to Joseph, Isaac, Israel, Abraham, and Benjamin. Raised in New York, Lionel, like his father and his grandfather, Isaac Moses, was involved in the China trade, traveling to Macao on business several times. In 1857, he married Selina Seixas, granddaughter of Gershom Mendes Seixas. They had seven children, including Sarah, Blanche, Gershom Arnold, Brandon, Lionel Jr., Selina, and Raphael, whom they raised in New York.