Board Thread:Manga/@comment-29919227-20160909220906

In my opinion this theory make no sense at all for the simple reason that Zeke is about the same age as Grisha if not older. Plus, we have no reason to think they are father and son in the first place. The only way this could be posible is if the titan powers stop the ageing process of its users, which can be consider another form of regeneration. So, if Zeke is Grisha's son then he must have gained his titan powers many years after his father. This is very unlikely though, because Grisha had been living inside the walls for aproximately 20 years and no one seem to have noticed him not ageing.  