The Lineage of Kohanim
Although the Jewish people once consisted of twelve tribes, today we are left with only three divisions: "Kohen," "Levi" and "Yisrael". In fact, today we are essentially left with only two of the original twelve tribes, as both "Kohanim" and "Leviim" descend from the tribe of Levi. It is commonly assumed that the "Yisrael" category is made up from the remnants of the tribe of Yehuda and Benjamin, with most of the other tribes having truly become the "Ten Lost Tribes".
It is vital that one claiming to be a Kohen is certain of his status. This is because it is generally only Kohanim who are subject to ritual requirements and restrictions. For example, in the event that the Kohen who officiated at a Pidyon Haben ceremony was actually disqualified or blemished, even unknowingly, the entire ceremony would be rendered invalid. Indeed, some authorities suggest that a father should redeem his firstborn son from as many Kohanim as possible, lest the Kohen who officiated at the Pidyon Haben was not a genuine Kohen.[1] So too, one who is truly a Kohen, though for whatever reason is unaware of this, would be in violation of many Biblical prohibitions every time he attends a funeral or enters a cemetery.
Although one who believes he is a Kohen must conduct himself accordingly, the question has been asked many times: How can we be so certain that after so many centuries the chain of lineage has been authentically and properly maintained?
Indeed, a number of authorities rule that the tribal designations in use today are merely "assumptions" with no halachic certainty as to their accuracy. In fact, many authorities assert that most Kohanim today are likely not of pure lineage.[2] Already in the late Biblical era, and certainly in the Talmudic era, there was considerable doubt as to who was truly a Kohen.[3] As a result of this uncertainty there are a number of mitzvot which are no longer performed in their entirety such as ma'aser, teruma, and challa.[4] Similarly, many authorities rule that Kohanim today are not entitled to all the rights and honors that Kohanim commanded in Biblical times.[5]
Nevertheless, there are authorities who maintain that one who claims to be a Kohen based on family tradition can be accepted as one without further questions or concerns.[6] As such, anyone who claims to be a Kohen is permitted to perform the Birkat Kohanim in the synagogue.[7] It might just be that today's practice of honoring a Kohen with the first Aliya at every Torah reading is merely a custom that was instituted in order to keep the ancient tradition alive.[8]
It is interesting to note that only the testimony of two witnesses can truly certify a person as a Kohen. Not only would these two witnesses be required to testify that the person in question and his father are Kohanim, but they would also be required to give evidence that they descend from Kohanim who served in the Beit Hamikdash.[9] Obviously, this is something that is simply not possible to prove today. In ancient times every family possessed extensive documentation attesting to their pedigree which was passed down from father to son.[10]
One who has conducted himself all his life as a Kohen is not permitted to later claim that he was mistaken and is actually not a Kohen. One who does so is to be suspected of ulterior motives such as a desire to marry a convert or a divorcee.[11] There is a view that one who was raised in a completely assimilated or unobservant family should not necessarily conduct himself as a Kohen even if his father should tell him that he is one.[12] One should seek rabbinic guidance in such a situation.
[1] Sheilat Yaavetz 1:155; Pitchei Teshuva, YD 305:12.
[2] Rivash 94; Maharashdam, EH 235.
[3] Nechemia 7:63-64; Ketubot 24b.
[4] Darkei Moshe, OC 457:4.
[5] Rambam, Hilchot Issurei Biah 20:1-4.
[6] Be'er Heitev, EH 6; Chatam Sofer, YD 336; Knesset Yechezkel 56.
[7] Rema, EH 3:1.
[8] Maharashdam, EH 235.
[9] Tur, EH 6:3; Perisha, EH 6:6; Middot 4:8; Sifri, Devarim 17:18.
[10] Rashi, Bamidbar 18:1.
[11] Maharit 1:147.
[12] Igrot Moshe, EH 4:11; Beit Avi 5:134.