Yes, there are. Hera, because she's the Goddess of Marriage and so does not screw around like her husband does, so she never sires any demigods. Artemis, because she's supposed to be an eternal maiden (eternal virgin). Dionysus, because he's the camp director and is only camp director as punishment for chasing an off limits nymph and pissing off Zeus (he's been there too long to of sired any kids that would be in the 16-25 age range, though in the books he has a few kids running around the camp).<br/><br/>Other than that, the others are good to go.