Board Thread:Lore Discussion/@comment-24810427-20140107220735/@comment-13446185-20140119161436

Azrael8472 wrote: Ketick1998 wrote: No, he is a part of the direct bloodline, whereas Cephorus down to Martin is not the direct bloodline. Page on Shornhelm  - As that states, he was adopted and not of actual Septim descent, hence why he was disinherited by the Elder Council. Also his father, Uriel Septim IV was not of Septim descent either, instead being the son of Empress Katariah (a Dunmer) and a consort.

It says nowhere that he was ever adopted, just that his cousin Cephorous II was more related to Tiber Septim than him.

"The Council's last victory over Uriel IV was posthumous. Andorak, Uriel IV's son, was disinherited by vote of Council, and a cousin more closely related to the original Septim line was proclaimed Cephorus II in 3E 247."

-Brief History of the Empire, Book III

Never reference wiki pages as they can't always be considered reliable. Instead look to see if the line you are refering to has a source and then check that source to see if the lore lines up, if there is no source then what is written on the page could possibly be wrong.