@OP :
When Tobirama and Minato met in recent manga, Tobirama was like, who the hell are you?
so NO.
I dont think that they are related LIKE THIS. The time difference is too big. Minato can be one's son, and that one can be the grandson of the Second Hokage. You know, Hashi and Tsunade-like stuff.
I would not see anyone suited better than Jiraiya to be Minato's son. Maybe he doesn't even know about this(I mean, nowadays, lots of people dont even know if they are parents, and I have met an example), and maybe the mother doesn't know either.
I would speculate the fact that both Tsunade and Jiraiya had feelings for each other, and both liked to drink. But it would only bore me and you too.
So, anyway, it would be: Tobirama=>his son/daughter=>his gradson/granddaughter=>Minato.
I think that both Minato's parents must be some badasses, because almost no one(talking about legends here) in Naruto is born from average parents.
It would be some irony here too, because Jiraiya tought of Minato as his own son, and Naruto thinks of Tsunade as his grandmother. And for Naruto to be the SO6P, it would be weird to be only 50% uzumaki(not even pure 50% Senju)
Feel free to flame me.