Traditionally, a kohen (if one is present) is called for the first section (aliyah), a Levite for the second reading, and an "Israelite" (non-kohen, non-levite) for all succeeding portions.
Traditionally, only a man can be a kohen, and the status is transmitted from a father to his son. The daughter of a kohen traditionally has special obligations and privileges, but these last only until she marries – and she does not pass these down to her own children.
The Kohen is treated with respect and is honored in many areas of Jewish ritual life. When the Torah is read, a Kohen is honored with the first reading, and a Kohen is called upon to recite Grace After Meals.
The only valid method of being a Levite (or Kohen) is to have an unbroken tradition, passed from generation to generation, stretching back to the time of Moses.
Who is a Kohen, a Jewish priest? Technically speaking, of course, the Kohen is a member of the priestly tribe of Israel descended from Moses’s brother Aaron and Aaron’s sons—the first Kohanim.
Who is a Jew? Who is a Kohen? | JNS | clevelandjewishnews.com
Kohen is the Hebrew word for "priest", used in reference to the Aaronic priesthood, also called Aaronites or Aaronides. They are traditionally believed, and halakhically required, to be of direct patrilineal descent from the biblical Aaron, brother of Moses, and thus belong to the Tribe of Levi.
Who is a Kohen, a Jewish priest? Technically speaking, of course, the Kohen is a member of the priestly tribe of Israel descended from Moses’s brother Aaron and Aaron’s sons—the first Kohanim. Today, scientists claim to be able to detect the “Kohen gene” in those descendants’ DNA.