Why were ancient Greeks pedophile and homosexual?
Not all of them were — obviously not all men in a culture can be truly homosexual — and Greek homoeroticism and pederasty seem to have been confined to the upper classes in certain areas, though we still don’t know enough about it to be sure. Outside of that culture, it wasn’t particularly common as far as we can tell. It involved an institutionalized, cultural view, first, that men were superior to women and that love between men was therefore superior to love between men and women, which didn’t involve much more than reproduction. (Greek women were made to live far more circumscribed lives than men were; they were really treated rather badly as compared with Roman women.) Second, the idea was that an older man became a mentor to a young boy, teaching him a wide variety of things about life, sex, etc. This is a highly simplified view I’m giving you. There are sites on the subject and also books.