[quote=Enalais]
There sure are a lot of Zeus kids for children of one of the big three.
[/quote]

Percy did make the Big 3 annul the oath they made saying they'd never have children, stating that it never worked in the first place. Zeus was also a pretty lustful guy, if not the most lustful god out of his brothers, so it doesn't strike me as too odd that he has a lot of kids.