Shia Muslims, in general, believe that the progenitors of Yazid did not convert sincerely and remained hypocrites. I personally have bigger fish to fry, so I don't think on it much.
Our beliefs regarding the ancestors of Prophet Muhammad and Imam `Ali are also different from those of Sunni Islam.
Some of our texts relate that the real name of `Abdul Muttalib was Shaybat al Hamd. Here is a genealogy that some of our `ulama have gathered for Prophet Muhammad. Prophet Adam, Shith (Seth), Unash, Qaynan, Mahla'il, Yarid, Ukhnakh (Idris or Enoch), Mattushalakh (Methusaleh), Lamk, Nah (Nuh, or Noah), Sam (Shem), Arfakhshadh, Shalikh, Had, `Abir (Prophet Bud), Faligh, Ar'awa', Sarakh, Takhar, Tarih, Ibrahim (Abraham), Isma`il (Ishamel), Qaydar, Hamal, Nabt, Salaman, al Hamaysa`, al Yasa` (possibly Elisha) , Udad, Udd (`Adnan) Ma`ad, Nazar, Madhar, Ilyas (possibly Elijah), Mudrikah, Khuzaymah, Kinanah, Nadhar, Malik, Fahr (possibly Quraysh), Ghalib, Lu'i, Murrah, Kilab, Qusay (possibly Quraysh), Mughirah ("`Abd Manaf"), `Amr (Hashim), Shaybat al Hamd ("`Abdul Muttalib"), `Abdullah, Prophet Muhammad. We believe that Shaybat al Hamd (`Abdul Muttalib) was a Hujjat of Allah and that Abu Talib was his successor.
We Shia Muslims believe that the ancestors of Prophet Muhammad and Imam `Ali were monotheists. Some of the ahadith from our books on the subject follow.
Imam `Ali also referred to specific members of the lineage of Prophet Muhammad: "By Allah, neither my father ever worshipped the idols, nor my grandfather 'Abdul Muttalib, nor his father Hashim [`Amr], nor his father `Abd Manaf [Mughirah]. They prayed facing towards the Ka`bah and followed the religion of Ibrahim." Ibn Abbas narrated that Prophet Muhammad said: "Allah sent me to the earth in the loins of Adam and transferred me to the loins of Abraham. He continued transferring me from the distinguished and exalted loins to pure wombs until He created me from my father and mother, who never met unlawfully."
In these matters, Shia Islam and Sunni Islam are differentiated from each other.