VDarashta VChakarta: Baal Teshuva - Are You Sefardi or Ashkenazi?
If a person of Sefardic descent becomes a Baal Teshuva under the influence of an Ashkenazi Rebbi (or vice versa) should he keep the minhagim of his Rebbi or must he keep the minhagim of his family despite the fact that they were not religious?
The V'Darashta V'Chakarta (YD 29) brings from Rav Ben Zion Abba Shaul who quotes a Shut HaRashba (1:353) that although one may rely on the psak of their Rebbi (even though it is not the way we paskens L'Halacha) this is only if the Rebbi is paskening on his own judgment. However if his psak is based on the minhag of the Rebbi's family you cannot rely on it but must keep to your own family minhagim since you can only rely on your Rebbi and not your Rebbi's ancestors.
He therefore concludes that even a Baal Teshuva must keep the minhagim of his ancestors regardless of the fact that he was educated different minhagim and despite the fact that recent generations chose to not to practice any minhagim or any form of Yiddishkeit.
He also says based on the Igros Moshe (OC 2:24) that if your father or grandfather changed the minhagim of their predecessors you may follow the original family minhagim and not the minhagim you were raised with.
Important Note: We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. Please also understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.