How do you find out which one of the 12 Tribes of Israel you come from?

Answer 1

Short answer: you can't know for sure unless: 1) You're a Kohen or Levi

2) You do serious research into your earliest-known ancestors and their records and/or gravesites.

The Tribes of Israel today are the Jewish people. The great majority of Jews today, some 80% or so, are descended from the tribe of Judah (plus converts and descendants of converts). The remaining 20% include Levites (from the tribe of Levi), Cohanim (also a part of the Levites), the entire Tribe of Benjamin, and a small percentage from every one of the remaining tribes. (When the Ten Tribes were carried off into Assyria and didn't return, some of them had already mixed into the tribe of Judah before that, through marriage and through large-scale migration [e.g. 2 Chronicles 15:9]. Also, the Talmud relates [Megillah 14b] that, one century after the Ten Tribes were exiled [and their location was still known], Jeremiah journeyed to where they were and brought some of them back to Judea. Thus, today's Jewry includes a small percentage of every one of the Lost Tribes. [See for example the Talmud, Pesachim 4a.])
As to the location of the bulk of the lost Ten Tribes, because of the lack of a continuous tradition in this particular matter, we can only speculate. Some well-known claims, such as the suggestion that the Native Americans or African Americans are the Lost Israelite Tribes, we can confidently dismiss offhand; and DNA analyses have also debunked such ideas. Other claims, such as that which has been suggested concerning the Pathani (Pashtun), are less far-fetched but must for the time being remain nothing more than a guess.

See also:

Jewish history timeline

Are Hebrews Israelites and Jews the same people?

Answer 2

In the great majority of cases, that information has been lost over the two thousand years of exile. Most of us are from Judah, while Kohens and Levis are from the Tribe of the Levites.

Answer 3

no