I know that Astolfo is gay/transexual because aside of wearing femenine outfits and having a femenine appearance, he (or rather she, though I think they call him a 'he' in the anime), he actually kinda falls in love with the protagonist in the Anime, who is a male. And also doesnt feel ashamed of being naked in front of Jeanne, who is a girl.
@enigmatico He is very explicitly male, and refers to himself as male several times throughout the series. He crossdresses because he thinks it's cute, and he does whatever feels most right at any given time without any deeper thought or reasoning.
@enigmatico@Galena The similar version of this is da Vinci... who thinks woman are so cute he transforms into one. At least I believe thats the explanation in F/GO. Except I think da Vinci *is* trans, astolfo is just a cutie
@caseyp@Galena The explanation FGO gives is that, he is a complete pervert who liked the Mona Lisa so much, he transformed into the Mona Lisa when summoned.