Just my ten cents,
The family, clan, and descendants of Umayyah disagree upon the assertions by others, Shia, and their sources.
Sunni Islam by scholarly consensus has Umayyah bin Abd Shams as Abd Shams's son, as biological, and that the scholar Hisham ibn al-Kalbi as untrustworthy, including his genealogies between Adnān and Ishmael, as a fabrication.
It is 'only' the sworn enemies of the Umayyad Empire, Shia, whom are a minority, based upon this single source (shared by Wikipediia which does not discuss this known contention), not contemporary, and bias, and whom was also a known enemy of the Umayyad Caliphate and it's origin. This attack on umayyah's lineage was a slur, rather than fact, which by this time has become Shia history. Hisham ibn al-Kalbi sources were from Abu Mikhnaf, also supported the Abbasids versus the Umayyads.
Abu Mikhnaf is known to be weak and unreliable (Gibb, 1960 ["Abu Mikhnaf". In Gibb, H. A. R.; Kramers, J. H.; Lévi-Provençal, E.; Schacht, J.; Lewis, B. & Pellat, Ch. (eds.). The Encyclopaedia of Islam, Second Edition. Volume I: A–B. Leiden: E. J. Brill. p. 140. OCLC 495469456]).
It was immoral and illegal (pre- and post Islamic shariah) amongst the Arabs to change your father, or call yourself after a father that was not biologically yours.
If you are born without a father, you do not change your name to suit your adopted father.
If you are the son of "'bin' (son of) + insert your father's name".
If the father is unknown "bin + Abdullah" (even the foremost god of gods under paganism).
You may call yourself "'Abu' (father of) + insert your son's name".
You cannot call yourself "Abu + insert adopted son's name".
In difference, to blaspheme.
Shams was a pagan god, pre-Islam (Shams, female solar deity), it was common to name "Abd + insert Arab pagan deity" as a personal name.
Abd Shams was a popular name pre-Islam, in fact the Arabic language (in which I am fluent), has half the alphabet as Shamsiyah letters (feminine solar god letters), and Qamariyah (masculine moon god letters).
If the case were true, then why
Umayyah 'bin' Abd Shams, and not
Umayyah 'abd' Shams?
In Arabic, 'bin abd' clearly mean 'the son to the slave of'
Hisham ibn al-Kalbi must have thought his slur was ingenious.
If Umayyah was not considered the legitimate son of Adb Shams, then he would not have been able to become the leader of his clan based upon his lineage in which he was chosen, in order to be Caliph over the other clans.
Arabic tradition is unchangeable, even today many obstinate pagan traditions exist, even in the two holies, Makah and Madina, especially when it comes to elective clan-ship, leadership of clan, and fear of dissent and civil war (to the Saudi pleasure).
Personally I am annoyed at the lack of Sunni input to fight this, as if it wasn't needed, or wasn't their prerogative, based on the premise that Muhammad's words are simply enough in regards ancestry, and amongst religious committees making discussions on the topic a taboo.
