Zeus probably fathers more than 12 children per year ... what can I say ... he’s a romantic kinda guy.
As king of the Immortals, Zeus is one heck of a father figure ... he loves and protects most of his children but he can’t avert Fate from making some of their lives miserable ... of all his kids, Zeus said that he found Ares to be the most disappointing ... as the god of War, Ares tends to be a bit brutal and unfeeling ... don’t get me wrong ... Ares loved and protected his children but most of them are a pretty sorry bunch.
Anyway ... no matter how you count’ em up ... the constant number of 12 Olympians has nothing to do with the number of Zeus’ children.