I would also like to point out the misconception on Zetsu's statement in 606:
There is a great misconception in Zetsu's statement in chapter 606 saying that Nagato is a descendant of the Senjus because he is of Senju Lineage:
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It is not Zetsu's statement that is erroneous but the interpretation of others, if we take the translation of lineage based on the context of Zetsu's statement in conjunction with Kushina's statement in a previous chapter, the most accurate meaning of lineage, based on context, is the anthropological definition of the word: Kinship/Consanguinity:
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Kushina said the Uzumakis and Senjus were distant relatives, the true intended meaning of the word "lineage" based on the context of Zetsu's statement was : Consanguine of being related by blood, not Nagato descending from the Senjus :
Nagato is a blood relative (lineage) of the Senju.
If the Senjus and Uzumakis descended from the same ancestor (Younger Son) then they will be close/immediate relatives, not distant relatives like Kushina said, which would contradict her statement and Manga canon, so it's logical to assume that the present day Uzumakis are "cousins" to both Senju and Uchiha since they did not descend from Rikudou himself but from Rikudou's relatives.
Also the original Japanese text of Zetsu in 606 is this:
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The original Japanese word that Zetsu used was
"血縁" or Ketsuen which translates as "Blood Relative" NOT
子孫 or Shison which means descendant.
Anyone who can read Japanese will tell you that Zetsu's statement only meant blood relations but not pertaining to descent:
