Responses
He lost his memory when he fell into that world.
He is also very young that time
I remember Cliff once thought that Leon's familiar with a sword, he's been teaching by someone at his world, so I think Leon's from noble/high-ranking magic family/clan and has been received extend education from his young age.
Sound unlikely but fair enough
Since Leon form never change that mean he from a race that male can pregnant from the start but he don't know about it since he isn't raise among his people