I get a lot of good questions from fans, many of whom are experts on Greek mythology. The most frequently asked question is this: If Athena pledged to be a maiden goddess, like Artemis, how can she have kids at Camp Half-Blood?
An excellent point, but no, the author did not forget this important fact. I'm keenly aware of Athena's pledge never to marry. It's one of the things that makes her such an interesting goddess, since unlike Artemis, Athena frequently seeks out the company of clever men, and takes their interests to heart, as she did with Odysseus.
In Percy Jackson book 4, this very question comes up in a conversation between Percy and Annabeth, but for those who can't wait, here's the author's explanation.
Athena, as you may know, was not born in the normal way. She sprang from Zeus's head in full battle armor. Her children have similar magic births. They are the product of purely intellectual affection Athena sometimes bestows on men of great cunning. Every offspring of Athena is literally a "brain child." A child of Athena is meant to be a gift to the mortal father -- a combination of the goddess's divine abilities and the father's mortal ingenuity. That's the technical explanation. The simple answer: When I was writing the series, I knew Athena was simply too cool not to have kids at camp, and so I thought up a way to make it happen!
I hope that provides an answer to those who were wondering. Thanks for all your great questions, young classicists!