Question: If a non-Jew converts according to the standards set forth by Halacha in Israel and he originates from an Ashkenazi country (Europe), may he conduct himself according to the laws and traditions of Sephardic and Middle Eastern Jews who have accepted the rulings of Maran Ha’Shulchan Aruch upon themselves or must he follow the laws and customs of Ashkenazim who have accepted the rulings of the Rama?
Answer: The Talmud and Poskim state clearly in several places that “one who converts is tantamount to a newborn baby.” We derive several laws from this statement. One of them is that although a non-Jew who curses Hashem is liable for the death penalty, if he converts, he is absolved from this punishment since after his conversion, he has the halachic status of a newborn baby.
Thus, since Maran Ha’Shulchan Aruch lived in the Land of Israel, was the chief halachic authority of Israel, and his rulings were universally accepted in the Land of Israel and the surrounding countries, Maran Rabbeinu Ovadia Yosef zt”l writes that a non-Jew who converts in Israel is tantamount to having been born there and must observe all laws and customs set forth by Maran Ha’Shulchan Aruch.
Although this individual’s parents originated from Ashkenazi countries, clearly, the convert need not even act stringently in accordance with the rulings of the Rama, for a convert retains no halachic lineage to his biological parents and according to Torah law, a convert may even marry his sister who has converted to Judaism along with him. (Nevertheless, our Sages enacted that a convert may not marry his relatives for another reason which we cannot discuss in the context of this Halacha.) Thus, a convert is not considered a child to his non-Jewish parents according to Halacha and he is therefore, he is certainly not obligated to follow the laws and customs of the lands where his parents originated from.
Summary: A non-Jew who converts in Israel must observe all of the laws and customs set forth by Maran Ha’Shulchan Aruch, who was the most outstanding halachic authority of the Land of Israel. He must also pray according to the Sephardic version of prayers which the more correct version according to the saintly Ari z”l. There is no halachic consideration regarding the convert’s country of origin, whether he is of European or Middle Eastern descent and he must follow the customs of the Land of Israel.