Is this ruling normative Judaism? No! An Orthodox rabbi tells me: “No it is not normative. He actually has a great deal of influence on many people. It is one of these things which is found the talmud which is absolutely not law nobody really recommends it today and yet he thinks it’s wonderful thing I love the part where he guarantees that will be no illnesses and no genetic problems. Brody is the one translates into English lots of the writings of Breslin specifically the teachings of Rabbi Arush.”
An Orthodox rab tells me about the below: “That is correct, but today it is very rare, and was never very common, if there is a genetic problem would depend upon how often it occurred. You would have to contact a geneticist.”
Dear Rabbi Brody, am I allowed according to Halacha to marry my niece or my cousin? Would there be any medical or genetic dangers? Thank you, NK from the Great Neck area
Your superb question is mentioned in the Gemara, tractate Yevamot, 62b, on the bottom of the page. Indeed, our sages both encourage and bless anyone that marries a niece. Rashi states that the Gemara is referring specifically to the daughter of a sister; since a man naturally loves his sister, says Rashi, he will have a special affection for a wife who is the daughter of his sister. The Tosephot argue as follows: Rabbenu Tam agrees with Rashi, and says that the mitzva is to marry the daughter of a sister specifically (more than a brother), because the daughter of a sister will bring her husband good fortune and sons who resemble the father. The Rashbam disagrees with Rashi and with Rabbenu Tam, and says that marrying the daughter of a brother is just as good a mitzva as marrying the daughter of a sister. The Rambam, in agreement with the rationale of the Rashbam stipulates (Hilchot Issure Beia, 2:14), that it’s a “mitzvat khakhamim”, a rabbinical ordnance, to marry a niece, whether she’s the daughter of a sister or a brother. As far as practical Halacha goes, The Rama rules that Ikar HaDin (Principle Halacha) is, “It’s a mitzva to marry the daughter of a sister”, then adds, “There are those who say that it is also a mitzva to marry the daughter of a brother. (See Shulkhan Oruch, Even Ezer 2:6).” In other words, the Rama tends to agree with Rashi and Rabbenu Tam, but doesn’t ignore the Rashbam.