All who are prohibited to enter into the Congregation are allowed to intermarry with each other; R’ Yehudah prohibits [it]. R’ Eliezer says: Those who are definite[ly unfit] with those who are definite[ly unfit] is permitted. Those who are definite[ly unfit] with those who[se status is doubtful, those who[se status] is doubtful with those who are definite[ly unfit], and those who[se status] is doubtful with those who[se status] is doubtful are prohibited. Those who[se status] is doubtful are: a shesuki, a foundling, and a Cuthean.

One who marries the daughter of a Kohen must investigate her through four mothers who are eight; her mother, her mother’s mother, her mother’s father’s mother and her mother, her father’s mother and her mother, and her father’s father’s mother and her mother.  [If she is] the daughter of a Levi or a Yisrael, one more is added to them.