Juan Jose Leal was born circa 1757, the son of Juan Antonio Leal and Antonia Garcia.
In 1782, he lived in Mier. The church census recorded that he was single, español, and 25 years old. His household included 4 people:
Juan Antonio Leal, español, married, age 59.
Antonia Garcia, española, married, age 57.
Juan Jose Leal, español, single, age 25.
Jose Patricio Leal, español, single, age 22.