Board Thread:Naruto Discussions/@comment-1018594-20160409062530/@comment-3279282-20160622131715

Scratch the "possibly", the Kingin Brothers were confirmed to be descendants of Hagoromo.

The databook doesn't suggest that. First of all, the Six Paths Yin Power is something entirely different from Yin Release. Second, the databook implies that not only Uchiha and Senju, being Hagoromo's descendants, have access to Yin and Yang Release, but also other clans who are not Hagoromo's descendants (Nara, Akimichi). Yin and Yang are not rooted in Hagoromo, he was just the most proficient user of those chakra natures.