What was the relationship between Ezra and Aaron?
Ezra was a descendant of Aaron, the first high priest. Ezra 7:1-5
What the Bible says
Ezra 7:5
The son of Abisue, the son of Phinees, the son of Eleazar the son of Aaron the priest from the beginning.
Douay-Rheims Bible (Challoner revision), public domain.