Board Thread:Theories and Speculation/@comment-26636534-20180125151653/@comment-1872728-20180201022953

Kabuto had mastered Sage Mode, which is further improved with Jugo's Clan's Kekkei Genkai. He also had access to Hyuga, Kaguya, Uchiha, Senju, and Uzumaki Clan's DNA, as well as all the Tailed Beasts' chakra. In my opinion, at least genetics wise, he could very well be considered the closest thing to Kaguya.