Hi NanaR
This is what the Insight Volume 2 says on page 346:
1.
Mary the mother of Jesus. She was the daughter of Heli, though the genealogy given by Luke lists Mary’s husband Joseph as the "son of Heli." Says M’Clintock and Strong’s
Cyclopaedia (1881, Vol. III, p. 774): "In constructing their genealogical tables, it is well known that the Jews reckoned wholly by males, rejecting, where the blood of the grandfather passed to the grandson through a daughter, the name of the daughter herself, and counting that daughter’s husband for the son of the maternal grandfather (Numb. xxvi, 33; xxvii, 4-7)." It is undoubtedly for this reason the historian Luke says that Joseph was the "son of Heli."—Lu 3:23.
Mary was of the tribe of Judah and a descendant of David. Hence it could be said of her son Jesus that he "sprang from the seed of David accordingtotheflesh." (Ro 1:3) Through his adoptive father Joseph, a descendant of David, Jesus had a legal right to David’s throne, and through his mother, as the "offspring," "seed," and "root" of David, he held the natural hereditary right to "the throne of Davidhisfather."—Mt 1:1-16; Lu 1:32; Ac 13:22, 23; 2Ti 2:8; Re 5:5; 22:16.
If tradition is correct, Heli’s wife, the mother of Mary, was Anna, whose sister had a daughter named Elizabeth, the mother of John the Baptizer. This tradition would make Elizabeth the cousin of Mary. That Mary was related to Elizabeth, who was "from the daughters of Aaron" of the tribe of Levi, the Scriptures themselves state. (Lu 1:5, 36) Mary’s sister, some have thought, was Salome, the wife of Zebedee, whose two sons, James and John, were numbered among Jesus’ apostles.—Mt 27:55, 56; Mr 15:40; 16:1; Joh 19:25.
This is the dubs understanding, I don't know if it is even close to being accurate. If I find anything else I will be sure to post it.
I.Wonder