Oz seems to conform to Victorian moral codes; for example, there is no mention of sexuality at all.
I think it conforms to codes for children's books in the early twentieth century, when the books were written (a bit late for Victorian, which the books aren't at all, I'd say). And if nobody has sex, there is at least an interesting example of gender-bending at the end of The Land of Oz when Tip (most reluctantly) has to transform into Princess Ozma.