Lev.21:14 required Levitical Priests to take a woman "of his own people" (H#'s 4480 and 5971-'am). Is this requiring that the priests take from (the tribes of) Israel in general or from the spacific tribe of Levi (or maybe the house of Judah)? I see All of Isreal told not to marry outside of the people of Israel (Deut.7:3-4) in a seperate context so when it comes to the Lev. Priests would this need to be repeated in context just in relation to them, or is something more detailed being said? 
I see a few terms that are used to mention "tribe": 'am (#5971), shebet (#7626), Matteh (H#4294- "figurative").
Num.1:47 But the Levites after the tribe of their fathers were not numbered among "them" (Israel). Mentions Levi in relation to "tribe"/branch of their fathers but goes on to say they are not to be counted among "them" (Ben- the sons/ tribes of Israel) IN RELATION TO INHERITANCE/ Territories (Deut.18:1-2) of Levi. So when it says they are required to take a wife of their own "people" what is being said? Is the "tribe" of Levi its "own" distinct "people"? Or in this case Is Israel the "people" being mentioned?

While physically being considered as a member of Israel (from birth) you are required to have a Mother that is of the decendants of Jacob, Tribal identity it through the Father (Num.1:18) Ab (H#1). so while Mary related to both Levi (through Mother) and Judah (through Father)  she and her seed would be considered as being of the tribe of Judah.

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 I recall -Dr. Michael Brown debateing -"Rabbi" Shmuley Boteach ("Is Jesus the Jewish Messiah?"). (link to debate pt 1, pt2)

-Brown:

....."The Scriptures went on to say he (Messiah) would have a priestly ministry, which is one of atonement ....." ..... "We see the theme of the son of David, and the anointed one, and as we read the scriptures, we see that he is priestly and he is royal. Zec.6 plainly says that he will sit as a priest on his throne, the one that is called the branch"...... "so first he came as a royal priest to make sacrifice and atonement for the nations of the world and his own people"

-Shmuley responded:

"When Mike Brown says that the Messiah will be a priest (btw Zech. 6:13 says), The Messiah must be from the house of David, a priest is from the house of Levi and David is from the house of Judah"

-Shmuley goes on to say:

"The Messiah must be a son of Jesse a son of David period"

Mashiach- HighEST Priest (LORD of Lords) and KING of Kings

Ps.110/ Zech 6:13

-King (Royal) Line:

Gen.49:10 Of Judah- Lk.3:33 by Mary/ Matt.1:2 by Joseph- legal father (inlaw)

Is.9:7 Of Jesse and David- Lk.1:32-33/ Lk.3:31-32 by Mary

Matt.1:6 by Joseph (legal)

-Priest (Annointed) Line:

Ps.110:4 /Heb.7 Forever after the order of Melchizedek (of which even the Levitical order paid tithes to). Heb.5:5-6 (NO need to relate Yeshua to tribe of Levi according to Heb.7!)

Ps.45:6,7 "scepter of righteousness" Messiah must be a "Righteous" (holy) king.

(suggested material: Biblical Christmas?,  Names within the line, Who is a Jew....)

Mixing disturbs the line /in relation to the lieniage/ but no ones birth is ever a sin.

Mixing/ Divorce/ Premarital sex?/ (personal studies: Yo’ash & Yehoyada 2 Sam.24:2-3/ Samuel's father 1 Sam.1:2/ Ruth / Rachab )