...but made like unto the Son of God; abideth a priest continually.
This reference, then, is the author's explanation as to how our anointed Savior's priesthood is similar to Melchizedek's, as being "Without father, without mother, without descent, having neither beginning of days, nor end of life...abideth a priest continually."
Our anointed Savior's only relation to Levi was through Mary's mother. Regardless, Joseph, Mary, and Mary's father, were all descended from Judah. Which brings us to verse 14.
"For it is evident that our Lord sprang out of Juda; of which tribe Moses spake nothing concerning priesthood."