Board Thread:Boruto Discussions/@comment-36351381-20180731025641/@comment-1872728-20180805133135

Jason of the Mangekyou wrote: all we know is that she is the granddaughter of the first hokage. What @Bambusek meant, was that Tsunade is the granddaughter of a Senju and an Uzumaki, which means one of her parents (the child of Hashi and Mito) will be half Senju.