Probably magic and the fact that he seems to be pretty consistently written as being a misogynist. At least, he doesn't seem to have a very high opinion of women. In the Justice League Dark animated movie, he was utterly disdainful of Zatanna until she started kicking his ass and he had an enchantment on his home that prevented any woman from speaking. In JLA, he was also quite disdainful toward Zatanna until she kicked his ass.
Though much is taken, much abides; and though
We are not now that strength which in old days
Moved earth and heaven, that which we are, we are,
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
--Lord Alfred Tennyson--