Kiddushin 75 - Those Whose Prohibitions are Uncertain

Rabbi Eliezer says: "Those whose prohibitions are uncertain, such as children born out-of-wedlock from unknown father and foundlings, can not marry each other or those whose prohibitions are certain." However, the law is not like this, but is like the Mishna which stated that they are allowed to marry e ach other.

Two opinions about Cutheans (dwellers of Shomron): that they they were insincere converts driven by fear of lions, and the special Kohamin who mixed with them were unfit; or that they were sincere converts and the special Kohanim among them were the best.