Originally Posted by Numinous
I only stumbled upon this thread now, and I say let's solve this... with logic!
1) Naruto is 17, Tsunade is 54, which is a difference of 37 years. That difference implies that if Tsunade is Naruto's grandmother, she'd have Minato when she was 14~23 years old and Minato the same thing.
2) Unfortunatly, the only related thing related to age that we know about Minato is his academy graduation age, which is 10.
3) Forgetting Kekkei genkai geniuses (*cough*Neji and Itachi*cough*), the minimum time between Genin and Jounin is 8 years, as seens in Kakashi (graduated at 5 and promoted to Jounin at 13). This means that Minato was at least 18 when he formed his team with Obito, Rin and Kakashi.
4) Minato would be at least 26 in the events of Kakashi Gaiden, and Kakashi was 13.
6) Since their age difference is at least 13 years and Kakashi is 30 years old, Minato, if he was alive, would be 43 (and by that logic, the Kyuubi attack happened a few months after the end of the Third Ninja War, since Minato would be at least 26 when Naruto was born)
7) Tsunade would be 11 at max to give birth to Minato. I don't think normal women are fertile so young, so Tsunade can't be Minato's mother.
You can argue some of the points, but that's what I conclude from the data available.
I have to disagree with some points
1) Naruto's only 16
3) The minimum time between gennin and jounin varies. Considering Minato was a naturally talented genius, he could have easily been a jounin by the same age as Kakashi or even younger, regardless when he graduated the academy. Even Neji graduated the academy with his normal group at age 12, and only became jounin just recently. If Neji being a kekke genkai user made him an exception like Itachii, he would have graduated before the age of 12. It also depends on how soon one's sensei allows their student to take the chunnin exams first, as seen with Gai holding his squad back a year. This means we dont know how old Minato was when he became jounin or formed team Obito, but 18 sounds pretty good for becoming their squad leader. Still just a guess. It just sounds good. I can definitely see Minato as a jounin by the same age or sooner than Kakashi was made jounin.
4) Minato could just as easily be in his early 20s, at least 20 by the time of Kakashi Gaiden events
6) Again, Minato didnt have to be at least 26 and their age difference doesnt have to be 13 years. Their age difference could just as easily be 7 years. Kakashi only graduated team 7, but it was not his 1st time up for squad leader. Sarutobi showed Iruka that Kakashi had failed all his potential students in the past. So based on that, Kakashi was likely offered at least 2 different teams in the past, meaning at leat 2 years prior to getting team 7, he could have already been a sensei. Could have been even more years. Iruka's response definitely made it seem like Kakashi had failed quite a few potential teams in the past.
7) I didnt do the math, but Tsunade can easily be in her fertile teens by the time she had Minato and well pass 11.
If everyone is just playing the guessing game, Tsunade could or could not be Minato's mom. U cannot rule it out playing the guessing game with the limited info we have on Minato's age