When Jonas da Costa Senior was born on October 30, 1887, in Amsterdam, Noord-Holland, Netherlands, his father, Jacob, was 38 and his mother, Eva, was 28. He married Sophie Mok on January 31, 1912, in his hometown. They had one child during their marriage. He died in August 1942 in Oswiecim, Malopolskie, Poland, at the age of 54.